UK: port the #1095 fixes that need no new policyengine-uk release

[juaristi22]

This is the third #1095 ports PR. It covers every actionable item on #1095 that waits for no policyengine-uk release, on the locked policyengine-uk 2.123.0.

The branch is rebased onto main 977ac983a (after #1167, #1188, #1145 and #1198). A calibration of this head passes all 7 calibrated-seam gates, as main does. Its loss is 0.00586 against main's 0.00611.

Before any national build: the renewals of the measure exclusions that expire from 15 October. After merge, as for #1100 and #1121: the signed-difference entries for the new and changed columns (D1, D5, D3, D4), whose drafts stay outside the repository until signed, then the national build and the certifier.

Summary

Root columns (D1, D5, D6)

• D1. UC gainful self-employment (Set UC gainful self-employment from the FRS main-job status policyengine-uk-data#525). uc_is_in_gainful_self_employment holds for a self-employed main job, whatever its profit, or for a side trade whose profit is above zero and above pay (UC Regs 2013 reg 64(a)). The engine's own rule read any nonzero self-employment income as gainful, so a trader at a loss never met the minimum income floor.
  • SPI-channel rows keep their donor's employment status but draw new incomes that don't read it. So they take the earnings route alone, until the SPI draw follows employment status (Draw SPI incomes within earnings groups set by FRS employment status policyengine-uk-data#529, UK spine: composition-faithful SPI income draw — bridge predictors and rank-preserving replacement (with-children UC residual) #840).
• D5. Children placed by a local authority. is_looked_after_by_local_authority marks foster children under 16, whom the FRS puts in the carer's benefit unit. The engine counted them as the carer's own children in its child tests. At 16 or over the FRS makes a foster child with a local authority allowance a separate benefit unit, so the rule stops there.
• D6. Loss-making landlords keep the CGT residential signal. UK FRS spine: stop counting lodgers' rent and property losses as property income; sub-letting rent for every tenure #1081 counts a letting loss as zero property income, so those landlords lost one of the CGT split's two residential signs. An internal flag, dropped at export, restores it for FRS rows. A redrawn SPI row drops its twin's flag, since its property income is an SPI donor's.

Take-up and capital (D2, D3, D4)

• D2. The UC take-up population is benefit units with a UC claimant or partner aged 18 or over and under Pension Credit qualifying age, the age half of the engine's is_uc_eligible (Supply is_hbai_dependent_child from the FRS and move targets and imputations off the deprecated is_child/is_adult policyengine-uk-data#486, Supply is_claimant_or_partner from the FRS adult table policyengine-uk-data#524). An engine lockstep test names the two cases it doesn't mirror: reg 8 claimants aged 16–17, and mixed-age couples on the Pension Credit route. The contract's population text is re-signed with the rate unchanged.
• D3. Property in recorded capital. UC and Pension Credit recorded capital add the household's countable property to the financial carrier. The engine replaces every capital source with the recorded figure, and the FRS capital question holds no property.
  • Who holds it. The household reference person's benefit unit holds all of the household's property, and no other unit records any (María's ruling of 2026-10-12). Each means test counts the claimant's and partner's own capital, and WAS records property for the household. The engine's proxies share it over every claimant or partner, which puts a parent's property on an adult child's claim; they apply to fewer than 10 units.
  • At what value. 90% of its value: market value less 10% for the costs of sale. Secured debt is not on the frame and goes with the WAS property draw (Value means-tested capital less 10% sale expenses and secured debt (UC reg 49 and legacy equivalents) policyengine-uk#1969 is the engine side).
  • A consequence. The reference person is the householder with the highest income, who is not always the owner. Where that person is of working age, the property of a pension-age unit in the household is recorded on the reference person's unit, and no Pension Credit assessment counts it. On the head's spine, 0.04m pension-age benefit units are in such a household.
  • A unit that reports Universal Credit keeps its receipt and records no UC property. DWP assessed its capital to pay it, and the property is imputed without that receipt.
  • For Universal Credit, D3 is complete only after the next engine bump. policyengine-uk 2.123.0 holds uc_reported_capital flat in its dataset projection, while Pension Credit recorded capital and the property columns project by GDP per head. So in 2025 and later the same property counts at a lower value for UC than for Pension Credit. policyengine-uk 2.124.0 projects it too (Record benefit-unit capital once; derive UC and Pension Credit reported capital from it policyengine-uk#2201).
  • The reporter redraw screens an FRS unit that reports UC on its carrier alone, so that unit stays in the training set.
  • The uk_uc_capital_coherence gate re-derives both capitals with the same rule, and now checks Pension Credit capital.
• D4. Pension Credit take-up (Solve Pension Credit take-up over entitled benefit units policyengine-uk-data#510) is solved over Great Britain, where DWP's rates apply, and drawn UK-wide. Units not entitled are drawn at the 37% rate, so a reform that entitles them pays them. Entitlement is read at the calibration year, on the frame policyengine-uk projects there from its survey year.

Targets (T1–T6)

• T5. The 13 HMRC SPI savings-interest band targets reach 2025 in two legs (Regenerate the uprating factor table from policyengine-uk's load-time uprating policyengine-uk-data#541): ONS household interest income to the dataset's year, 2024, then GDP per head, the index policyengine-uk's dataset projection applies. Their factor moves from 1.182 to 1.192. The SPI donor rebase is unchanged.
• T6. The PIP daily-living caseload rows take obr.pip's England and Wales scope, resolve, and are then held as diagnostics on obr.pip (T6b): fitting them took the calibration over the weight-ratio fence (below).
• T3. obr.council_tax binds OBR table 4.1 row 15, England, Scotland and Wales receipts, over Great Britain's households. Row 19, bound before, adds Northern Ireland domestic rates and two adjustments no household carries (£1.34bn).
• T4. obr.ni becomes a diagnostic beside the three class rows. It's a cash total against accrued class rows, and it carries items no household pays (Stop calibrating OBR total NICs on ni_employee policyengine-uk-data#537).
• T2. The salary-sacrifice relief bands bind by income tax rate class (Restore HMRC salary sacrifice relief calibration targets policyengine-uk-data#533). The measure resolver gains a declared allocation: the rise in tax on earned income, bracket by bracket, under each person's rest-of-UK or Scottish schedule. uk-data's worked examples reproduce exactly. The measure refuses if a person's classes stop adding up to the engine's earned_income_tax. The all-rates total becomes a diagnostic, and the three exclusions retire.
• T1. UC award bands read in whole pence (Calibrate GB universal credit to one OBR total; reach the UC payment top band policyengine-uk-data#530). The "£2,500.01 or over" band stays unbound (below).

What the measurement changed

The first head bound the top UC band and fitted the two PIP rows. It failed two gates, and calibrate-only runs on its spine attributed each failure to one change.

• The PIP rows fail the weight-ratio gate. They fit within 0.1%, but on that spine uk_weight_ratio failed with them and passed without them. So T6b holds them as diagnostics.
• The top UC band costs the UC total. Unbound, the calibration holds 2.57 times DWP's count of lone parents in it and 1.99 times for couples with children, £13.1bn of UC, and reaches OBR's £76.1bn. Bound to DWP's counts, obr.universal_credit falls to −5.6%. Couples without children have fewer than 10 households in the band. So the band stays unbound, as on main. The awards below it are too low for DWP's band counts and OBR's total to fit together, which needs its own issue.
• D3 for every unit put UC reporters over the capital limit. On the Arm 2 spine, 30+ FRS-channel rows that report UC went above £16,000 through property alone. About three quarters were in households with no property income, and half in households with two or more benefit units. Hence the reporter rule.
• D1 from the donor's status flagged SPI rows with no trade. 1.67m weighted SPI-channel people were flagged with no self-employment income. Hence the earnings route for SPI rows.

María ruled on all four on 2026-10-10. The sparse-band support floor the plan added moves to its own PR.

Review round 1 (11 October)

An adversarial review of cf42d8a7a is in the comments. Five commits answer it.

• D4 read 2024 values against 2025 rules, because the engine adapter stamped the frame with the entitlement year. The frame is now stamped with its survey year and projected. Units entitled to Guarantee Credit fall from 1,354k to 1,247k.
• T5 rebased the 2022-23 SPI donors to 2024 by GDP per head, and so dropped the rise in savings interest of those years (ONS household interest income is ×1.99 from 2022 to 2023). The donor rebase is main's again, and only the projection leg of the band targets uses GDP per head. This was the cause of the pull on the top income cells that the first write-up assigned to T5 as a side effect.
• D3's training screen dropped FRS units that report UC and hold imputed property. It now screens them on their carrier.
• D6 let a redrawn SPI row keep its FRS twin's landlord flag, which turned the CGT residential signal on for 695k weighted SPI-channel people. Redrawn rows now drop it.
• T2 now checks its classes against the engine's earned_income_tax.
• W. The branch retired the West Midlands deferral and then restored it. Both commits are overtaken: UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 retired the deferral on main, and One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198 reconciles the cell, which is at +0.2% on this head.

María's rulings of 12 October, from the review:

• D3, who holds the property. Shared pro rata, £104bn of property sat on 0.99m benefit units that are not the household reference person's. Now the reference person's unit holds it, at 90% of its value. Measured before the rebase, on the recalibrated head:
  • units over the UC capital limit through property fall from 2.65m to 1.50m, and almost none of them is another unit than the reference person's (1.16m before);
  • in households with other property, units that are not the reference person's are paid £1.16bn of UC across 216k units (£0.60bn across 85k before). The UC total is on target both times.
• Secured debt waits for the WAS property draw. On the WAS donor file, mortgages on other property are 26% of its value.

Re-review and rebase (12 October)

A re-review of bcbe274b2 is in the comments. It asked for the rebase, a new measurement, and five smaller changes.

• The rebase. The 24 commits are replayed onto main 977ac983a. One commit, 4dac8a31d, then sets the tree to a merge that was regenerated and tested as a whole: hand-written files merged by hand, generated files regenerated on Chronicle 942a1fa. So the branch does not bisect across that commit.
• The merged surface: 1,279 active references (main's 1,281 less obr.ni and the all-rates salary-sacrifice relief), 396 contract targets and 65 measure exclusions.
• One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198's salary-sacrifice hold named hmrc.salary_sacrifice.it_relief_total. That row is a diagnostic here, so its id leaves the signed hold. The hold keeps the three rate bands and the employee NICs relief.
• D3's reference-person rule (N3, N4): two engine tests and the module text now state what the rule leaves. They cover the pension-age case above, and a unit on the unavailable sentinel, which stays on the engine's proxies beside a recording unit.
• T2's refusal (N5) allows £1 plus four float32 steps at the person's own amounts, since the engine computes in float32.
• The Pension Credit stage resolves its declared survey_year rules and refuses a frame from another year. The adapter's dataset_period argument has a named protocol.
• Main's new pins caught two things on the rebased branch, both fixed: a pinned kernel hash that a typing-only addition moved, and an import that One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198's coverage test wants declared.

Vahid's review (13 October)

• Small survey counts are in bands (item 1). The receipts and this description gave exact counts of survey records for small groups. They are now <10, 10–29 or 30+, as UK local: rerun the 2025 Autumn Budget constituency analysis on the local candidate to find data gaps and per-seat support before Budget day #1241 publishes support counts. The looked-after children rest on fewer than 10 survey households, so their weighted totals are removed.
• D3 and the engine projection (item 2): stated in the D3 summary above and under "Left for later".
• Give children recorded as aged 0 an age in months policyengine-uk-data#547 (item 3): named below as not covered.
• Engine version in the text (item 4): the lines this PR adds now cite the locked 2.123.0. The UC take-up citation, re-signed on 9 October against 2.122.2, keeps that fact and adds that 2.123.0 is the same.

Still open: the signed differences. The committed uc-reported-capital-net-new-column text predates D3, and its redraft waits for María's signature.

Where this departs from the plan

• D5 reads the foster relationship code alone. The FRS records few looked-after children (10–29 child records), and the carer's fostering allowance covers fewer still.
• D2 doesn't use Max's test scaffolding, which isn't on main. His uk-take-up-per-person-spa branch solves the State Pension age by date of birth and will need a rebase onto D2.
• D3 gives the property to the household reference person's unit at 90% of its value, where the plan mirrored each engine proxy (María's ruling of 12 October).
• T3 adds an exact-id geography pin: the substring rule would read "scotland" in the row's concept.
• T3 and T4 give their compile-parity rows their own rationales.
• T5 changes the projection leg of the targets only (review round 1).
• T6b lets a diagnostic reference carry a fact dated by month.
• T1 leaves the top band unbound, and the support floor moves out (above).

Measurement

Each arm was built and calibrated locally on Chronicle 942a1fa with policyengine-uk 2.123.0. The control is this branch's base, main 977ac983a. The head arm ran on the tree of e87e2ce7d; the commits after it change no stage and no target.

• Control (main 977ac983a). Loss 0.00611, 98.6% of 1,213 targets within 10%, ESS 5,195. All 7 calibrated-seam gates pass.
  • The earlier control, on 7639ef8b0, failed uk_weight_ratio. That failure is gone on main since Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167, UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 and One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198.
• This head. Loss 0.00586, 98.8% of 1,214 targets within 10%, ESS 5,129. All 7 gates and the certifier's input-mass gate pass, with no stale, expired or dormant exclusion.
  • obr.council_tax calibrates to −7.2% (control −9.7%), and obr.universal_credit, obr.pip and the three salary-sacrifice bands to within 0.1%.
  • 108 of 111 UC cells are within 10% (control 107). One cell moves the other way: dwp.uc.households_children_2, from −9.7% to −12.4%.
  • The West Midlands £12,570–15,000 income-tax cell is at +0.2% (control −0.2%), with no deferral.
  • The £500,000–1,000,000 employment-income band is at −3.4% (control −5.1%).
  • The largest error among the fitted cells is 15.9% (control 16.5%).
  • D3, at calibrated weights in 2025: 1.53m benefit units are over the UC capital limit through property, and fewer than 10 of them are not the reference person's. 10–29 FRS-channel benefit units that report UC keep their receipt.
  • On the head's export, uk_uc_capital_coherence and uk_take_up_signal pass. The arm pipeline leaves both to the certifier, so they were run with their own evaluators.
• Earlier arms, on the older bases d50220d1f and 7639ef8b0, are in the receipts. They attributed the first head's failures and measured the review's fixes and the D3 ruling.

Full numbers are in experiments/1095-uk-data-ports-3-receipts.md.

Testing

• Each commit of the earlier rounds: touched-surface tests. The rebased commits before 4dac8a31d were not re-tested one by one.
• This head (lanes run at 30ef5546f; the commits after it change the receipts, the version strings and the stage text regenerated from them, with 1,545 touched-surface tests passing):
  • the engine-free lane's 558 test files, with policyengine-uk blocked as in CI: 16,708 passed and 148 skipped. The three failures are environmental: the live Hugging Face pointer test fails on main too, the telemetry token exchange needs the hosted service, and main's US head-to-head scorer test needs Python 3.14.7;
  • the engine-uk lane's 43 test files, run in full: 191 passed;
  • against the pinned feed 942a1fa: the national compile-parity receipts regenerate identically, the committed references regenerate, and the diagnostics resolve their exact facts (59 passed, 2 skipped). One feed-gated test fails, and it fails on main 977ac983a in the same way: its gate call reads three 2023 land rows as fixture_only where the receipt signs them ledger_absent. CI skips that test.
• Lint and CI plan: ruff check and ruff format --check pass on the 67 changed Python files, and so do tools/ci_test_plan.py verify and tools/graph_acceptance_burndown.py --verify.

Overlaps and what follows

• Before any national build: the renewals of the measure exclusions that expire from 15 October.
• UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145, Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167, Bound native evidence by bytes, not by the schema item budget #1188 and One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198 are merged, and this branch is rebased onto them. From UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 it takes the empty target-fit register; from One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198, the reconciled surface, the holds register and feed 942a1fa.
• Left for later PRs: the sparse-band support floor, SPI incomes by employment status (Draw SPI incomes within earnings groups set by FRS employment status policyengine-uk-data#529, with UK spine: composition-faithful SPI income draw — bridge predictors and rank-preserving replacement (with-children UC residual) #840), the WAS property draw with the mortgages on other property, the UC awards below the top band, and the weight year.
• At the next engine bump: the D3 figures at 2025, such as the units over the UC capital limit through property, will move when uc_reported_capital starts to project (policyengine-uk 2.124.0). That release also adds benunit_reported_capital. D3 records two different figures (land counts for Pension Credit only, and UC reporters keep their receipt), so the spine keeps writing both columns.
• Not covered: Give children recorded as aged 0 an age in months policyengine-uk-data#547 (no child aged 9 to 11 months reaches the working-parent childcare entitlement). María ruled on 9 October that the fix belongs in policyengine-uk, whose childcare test should read age in months. No issue is filed for it yet, so "every actionable item" above does not include it.

Receipts: experiments/1095-uk-data-ports-3-receipts.md.

🤖 Generated with Claude Code

[juaristi22]

Independent adversarial review (Claude Code) at cf42d8a7a

Static review only. I read the code, the committed registers and experiments/1095-uk-data-ports-3-receipts.md against main 7639ef8b0, and the installed policyengine-uk 2.122.2 source for engine semantics. I ran nothing. CI is green.

Verdict. Most of the ports are sound:

• D1 and D2: the rules are as stated.
• D2 direction: mixed-age couples are correctly inside the UC population.
• Determinism: no new RNG streams.
• D6: the flag is dropped at export.
• T2: the rate-class arithmetic reproduces uk-data's examples by hand.
• T1, T3, T4 and T6: they do what the body says.
• Fixture: synthetic.

Three things should change before this leaves draft: D4 reads survey-year values against calibration-year rules, D3 adds gross property to recorded capital, and T5 changes the donor rebase in a way the targets can't absorb. One cross-PR collision with #1198 breaks the national compile whichever PR merges second.

Should fix

1. D4 reads 2024 values against 2025 rules.

   • Where: pension_credit_take_up.py:232 calls engine.materialize(with_saving, requested, entitlement_year). with_saving is the survey-year frame (time_period=period), and the adapter builds UKSingleYearDataset(fiscal_year=int(period)) from the requested period (microcosm-frame/.../policyengine_uk.py:172).
   • Effect: the frame's 2024 incomes, capital and State Pension are relabelled as 2025 inputs and never projected. On main, both the frame and the call were at the survey year.
   • Example: a single pensioner on the full new State Pension and nothing else is read at about £221.20 a week against the 2025 guarantee of £221.85, so is entitled. On the released file at 2025 the pension is £230.25 and the unit is not.
   • Consequences: the entitled set E is inflated. The residual rates, and the stage-gate receipt, describe a population the released file doesn't reproduce.
   • Fix: materialize at the survey year with the engine computing period 2025, so policyengine-uk projects the frame forward. If that's what uk-data does, cite it.

2. D3 adds gross property, not countable capital. It does so by mirroring the engine proxy, but the engine treats a recorded figure as already countable.

   • Gross value: UC_PROPERTY_CAPITAL_SOURCES sums other_residential_property_value and non_residential_property_value (Pension Credit adds owned_land) at market value (uc_capital_coherence.py:89-93).
     • UC Regs 2013 reg 49 and SPC Regs 2002 reg 19 value capital at market value less 10% for sale costs and less any debt secured on it.
     • A £120k buy-to-let with a £110k mortgage counts as about £0; this records £120k, so the unit fails the UC limit and Pension Credit deems tariff income on it.
     • was_wealth already draws other_mortgage, but only mortgage_debt reaches the frame.
   • Owners: _household_property_share splits a household's property over every claimant and partner in it (UC), or every member at or over qualifying age (Pension Credit). So an adult child's unit takes a third of the parents' buy-to-let; tests/engine/uk/test_uk_uc_capital_coherence.py:136 asserts the £66,667/£33,333 split. UC counts only the claimants' own capital (reg 18); Pension Credit counts the claimant's and partner's (SPCA 2002 s.5).
   • Size (receipts:108-112): £1,247bn of UC capital over 5.18m units. With the reporter rule, UC falls £0.80bn and 179k non-reporters lose UC.
   • What the reporter rule tells us: about 157k weighted UC reporters would have crossed £16,000 on imputed property, although DWP assessed their capital and paid them. That is evidence the imputed figure overstates countable capital. The rule protects reporters, but the same overstatement still applies to non-reporters.
   • Fix: net secured debt and the 10%, and assign property to its owning unit (the household reference person's unit, or WAS ownership where available) rather than pro rata.

3. T5's donor rebase drops a known surge that the targets already contain.

   • Where: SPI_INCOME_UPRATING_INDEX_OVERRIDES (spi_income.py:93) rebases the 2022-23 SPI donors' savings interest to 2024 by GDP per head (×1.09) instead of household interest income (×2.27). The commit says donors fall about 52% and the band targets 8.4%.
   • The problem: the engine-alignment argument (uk-data#541, uprating_indices.yaml) is about how policyengine-uk projects a dataset forward from its own year. The 2022 → 2024 donor rebase is history, and savings interest roughly doubled over it as rates rose. The 2023-24 SPI target base contains that rise; the rebased donors don't. So the solve has to make up about half of SPI savings interest through the weights, concentrated where savings sit.
   • What it explains: T5 alone moves the £500k–1m employment band from −2.5% to −13.3%, which an 8.4% cut to savings targets can't do directly. The head still has top income cells at −11.5% and −15.2%.
   • Fix: keep the household-interest index for the historical rebase to the base year and use GDP per head only for the projection beyond it. Or record why not.
   • Index pairing: the amount rows also stay on a flat index while their count rows grow by band. The implied mean per saver falls 4–13% above £30k, against about 1.00 for employment under the UK spine follow-ups after #1045: SPI band donors as a mass-conserving support channel, WAS tenure coherence, the residential draw's bound and Table 7 composition, then a national build #1063 rule. Dividends and property (UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145) have the same pattern.

4. Cross-PR: One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198's holds register refuses this PR's T2 in either merge order.

   • One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198's uk/uprating_holds.json:224 declares a hold on hmrc.salary_sacrifice.it_relief_total, which this PR turns into a diagnostic.
   • One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198's compile refuses a declaration that matches no held row (uprating_holds.py:177, "stale"), in both the full and national loaders. The two PRs touch different files, so git merges them cleanly and only the compile fails.
   • The "Overlaps" section mentions only UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145. One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198 also rescales the West Midlands cell W depends on (item 7).

5. The after-merge sequence needs the exclusion renewals first.

   • dwp.uc.households_housing_element expires 2026-10-15, ons.savings_interest_income 2026-10-22, and the two slc.borrowers.plan_2_* entries 2026-11-03.
   • apply_uk_calibration_measure_exclusions raises outside the window (measure_simulation.py:919-931), so any national build after 15 October fails until they're renewed.
   • This PR's own measurement relied on both near-term entries. T5 moves the model further from the D.41 row that ons.savings_interest_income excludes, so that entry needs renewing, not dropping.
   • Treat the renewal PR as a prerequisite, not a follow-up.

Minor

6. The measurement isn't of this tree, and the control is confounded.
   • Not this tree: "this head" solved on a7e5bc56f plus Bound native evidence by bytes, not by the schema item budget #1188's commit, with the spine from 0324e9e84. The W pass is a gate replay after the commit that retires the deferral.
   • Not in the repo: 0324e9e84, 341a02bd4, ae9795d7c, a42edaa9e and c7fe76e8a, and the scripts certifier_gates_check.py and uc_top_band_check.py.
   • Confounded control: the control is UK: port the remaining uk-data fixes tracked in #1095, engine items included #1121's head-r3, before Weight UK BRMA assignment by census private-rented households #1087's BRMA change merged. So every control-to-head delta also carries Weight UK BRMA assignment by census private-rented households #1087's unmeasured effect: loss, council tax −9.8 → −7.0%, minimum income floor 1.84m → 1.63m, and West Midlands +28.9 → +23.9%. The absolute head figures stand, but the attribution doesn't.
7. W's 1.1-point margin across the open PRs.
   • Retirement is required: the gate fails stale entries (terminal_gates.py:1029-1042).
   • Under One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198: the band bridge itl_income_tax_12570_vs_spi_region_12570 scales this cell's target by ×1.057 (55.15m → 58.31m), which on these weights would put it near +17%.
   • Under UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145: that PR deletes the same entry and measured the cell at +23.4% (and +26.8% on one arm). The combination is unmeasured.
   • Root cause: the design value is still 6.2× its target. Banding the regional cells on total income including other investment income, as the old deferral reason suggests, would fix the cause instead of the register.
8. The signed-difference step is not enforced, and one committed signature is now false.
   • Not enforced: spine_swap_signed_differences.json is read only by manual tools (verify_uk_spine_parity.py, compare_uk_h5_payload.py). The release cut already lists uc_is_in_gainful_self_employment and is_looked_after_by_local_authority as reviewed candidate-only fields.
   • False signature: the uc-reported-capital-net-new-column entry (:525) says uc_reported_capital comes "from the same frs_benunit_capital carrier". After D3 it doesn't, and its only check (that the column exists) still passes.
   • Question: why aren't D4 (would_claim_pc now drawn for 37% of non-entitled units) and T5 (SPI donor savings −52%) on the D1/D5/D3 signature list?
9. D3 reporter rule.
   • The share doesn't stay put: a reporter records the carrier alone, but policyengine-uk's household residual sums only recorded figures. So a co-resident unit with the −1 sentinel absorbs the reporter's withheld share through the proxy, which contradicts "the other units of its household keep their own shares".
   • Training screen: uc_reporter_redraw.py:280/381 applies carrier plus property to every training unit, including the reporters the stage protects, so real UC reporters drop out of the QRF training set.
10. D4's 37% draw has an Income Support side effect. policyengine-uk's income_support_eligible bars Income Support where meets_pension_credit_age_conditions & would_claim_pc, with no means test. So mixed-age couples on the Pension Credit route who report Income Support and aren't entitled to Pension Credit now lose Income Support 37% of the time. The population is small, but it's undeclared.
11. D5's under-16 cutoff (frs_relationships.py:193, below_age: 16) can only drop flags. It misses 16–19-year-old foster children who are qualifying young persons in the carer's unit, who are still looked after (Children Act 1989 ss.22, 105; UC Regs reg 4(6)(a)). test_uk_frs_relationships.py:437 pins a 16-year-old as not looked after.
12. D6 on SPI rows: the landlord flag is written from the FRS twin (frs_spine.py:661), and no SPI refresh rewrites it. So SPI rows whose drawn property income is zero keep the twin's flag and turn on the residential CGT signal. That's the "donor status says nothing about drawn incomes" problem D1 rules against.
13. T2.
    • Wrong comparison: the receipt compares the class sum with Δincome_tax, which differs legitimately through savings, dividends and HICBC. The engine variable the allocation re-implements is earned_income_tax, and comparing against that would catch schedule drift.
    • Untested diagnostic: no test checks that the it_relief_total diagnostic resolves. _diagnostic_reference_metadata turns a mismatch into unavailable without failing.
    • Question: does HMRC Table 6.1 classify relief bracket by bracket or by marginal rate? At design weights, basic reads 0.66×, higher 0.53× and additional 1.37×, which takes strong opposite reweighting to fit.
14. Stale text.
    • tools/build_uk_ledger_compile_parity_signed_differences.py:76 still says the savings rows are "uprated by the household interest index", and that's regenerated into the 13 rows' signed reason, whose values moved ×0.916. docs/uk-income-anchors-280.md says the same.
    • The changelog fragments carry intermediate counts (391/1,232, 390/1,231, "stays at 1,231") where the head is 388/1,229.
    • The W fragment's "+28.9% on main" is pre-Weight UK BRMA assignment by census private-rented households #1087.
15. Nits.
    • The D1 earnings route silently skips SPI rows if the column is missing (spi_income.py:2082), falling back to the engine default.
    • The D2 lockstep test narrowed from ages 0–100 to 14–90 without saying why.
    • T1 compares annual pence, not DWP's monthly pence (negligible).
    • income_tax_rate_classes.py:65-71 files a schedule's top rate as "additional" even at 40%.
    • The UC skipped-fact count changed from 12 to 8 on the same feed pin with no note.

Merge order with #1145, #1198 and #1167

• Feeds: UK: port the #1095 fixes that need no new policyengine-uk release #1200 is on 825406f, Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167 on 1ee7dfe and One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198 on 942a1fa, all on one line. Whichever lands first, the others regenerate their references, membership, parity receipts and uk_data_target_parity on the new feed, and re-measure.
• Regenerate, don't hand-merge: contract.py and its test pins, the coverage manifest, the H2 fixture, and the gates.json export-surface list (UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145's two property columns plus this PR's two).
• UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145: its _engine_scratch_frame change will also drop this PR's reports_rent_from_other_property from the calibration engine input. That's harmless, because no engine measure reads it.
• One consistent UK target surface: enforced cross-grain reconciliation, declared uprating holds, nation household controls and the 942a1fa re-pin (#1123 PR A) #1198: remove it_relief_total from its hold (item 4). It also adds income_tax > 0 to the same hmrc.spi.savings_interest_income binding T5 re-indexes. That combination, with the −52% donors, has never been calibrated.
• Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167: it excludes obr.vat, which removes this head's other near-bound cell (+22.7%), and its LCFS levels change the spine. So a combined calibration is needed.

Checked and fine:

• Counts: 1,168 targets = 1,229 active − 61 exclusions.
• Values: T3's £1.34bn (50.116 − 48.774), and T4's total at 1.0182× the class rows.
• T5's ratios: 0.916 on all 13 rows.
• T6: a month-dated fact reaches only diagnostics.
• Exclusions: the three salary-sacrifice exclusions were genuinely redundant.
• Mirrors: the coverage-manifest and gate digests move consistently.
• Take-up contract: its rate is unchanged at 0.55.

[juaristi22]

Re-review (Claude Code) at bcbe274b2

Static review of cf42d8a7a..bcbe274b2 against the review and the reply. I read the code and policyengine-uk 2.122.2's source, and ran nothing.

Verdict.

• Fixed: the three main items. D4 now projects the survey-year frame, T5's donor rebase is back on history, and D3 follows the ruling.
• Answered with reasons that hold up: item 10 (Income Support) and item 11 (D5 age).
• No regression, and no test edited to match a count.
• Not ready to leave draft: CI hasn't run on the D3 rewrite, the branch conflicts with main, and every figure is on the pre-Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167 base, while the head fails uk_weight_ratio and W sits just over the bound.
• Disclosure: a few disclosure-control items went to the author separately.

Previous items

#	Status	Note
1 D4	Fixed	materialize(..., dataset_period=) is keyword-only with default None, so other callers are unchanged, and a dataset year after the period is refused (policyengine_uk.py:85-109). The stage and the calibration resolver both load the survey year and compute at 2025. The engine test pins the pensioner case.
2 D3	Changed by ruling	The owner is FRS hrpid == 1, checked as exactly one per household (uc_capital_coherence.py:426-467), and property counts at 0.9 (:104). Pension Credit follows the same rule. The gate re-derives with the same functions and refuses a drift in the declared rule. See N3 and N4.
3 T5	Fixed	A declared composed index (hmrc_uprating.py:455-525): household interest to the dataset year, then GDP per head. The 13 amount rows move ×1.0086 against main, and count rows don't move.
4 #1198 hold	Fixed (text)	#1198 holds all four it_relief_* rows, so whichever lands second removes it_relief_total from it.
5 Renewals	Fixed	The description lists them first. Nit: main's W deferral (expiring 2026-11-03) isn't on the list.
6 Measurement	Partly	The control is now on the base, and the #1087 attribution holds: between d50220d1f and a469ebe3d the only first-parent change is #1087. But see N1 and N2.
7 W	Reverted	The register and its test are byte-identical to main.
8 Signed differences	Open, acknowledged	spine_swap_signed_differences.json:513-525 is now stale twice over (carrier and owner rule), and still nothing enforces it.
9 Reporter rule	Fixed	The redraw screens a UC-reporting FRS unit on its carrier alone (uc_reporter_redraw.py:386-399). The only remaining leak is to sentinel units, which is documented.
10 D4 and Income Support	Not changed, justified	In 2.122.2, meets_pension_credit_age_conditions gives a mixed-age couple the Pension Credit route only with the SI 2019/37 saving. That saving needs reported Pension Credit or pension-age Housing Benefit without an income-related benefit, so an Income Support reporter who isn't a Pension Credit reporter can't have it. The engine test pins it.
11 D5 age	Not changed, explained	frs_relationships.py:186-192.
12 D6 on SPI rows	Fixed	spi_income.py:2106-2128, graph.py:1023-1026.
13 T2	Fixed / partly	The per-person earned_income_tax check refuses beyond £1 (measure_simulation.py:741-763), and the top rate is fixed. The it_relief_total test is feed-gated and skips in CI, where the compile still turns a mismatch into unavailable.
14 Stale text	Fixed
15 Nits	Partly	D2 is back to 0–100, the top rate and 12 → 8 are explained, and D1's skip and T1's pence are kept with reasons.

New

Before leaving draft

• N1. CI has not run on the fix round.
  • 887d36de4, 78ea6b695, cf91835c9 and bcbe274b2 have no check runs. The last run was on 7b17c1d20, and the PR has conflicted with main since Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167 merged.
  • So the 20-file D3 change has been tested only locally. The rebase will trigger CI anyway, but it's worth knowing that this head has never been through it.
• N2. The merge gate picture is on a stale base.
  • The head fails uk_weight_ratio, and W is just over the bound, both measured on 7639ef8b0.
  • Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167 changes the solve: four new measure exclusions including obr.vat, the LCFS stage, and feed 1ee7dfe. So after the rebase W may go stale (the gate then fails the deferral) or stay over, and the weight ratio may move either way.
  • The ruling that this PR proceeds while main's breach is resolved separately exists only as text. No issue tracks main's uk_weight_ratio breach (I searched).
  • Open one and link it, and re-measure on the rebased tree before leaving draft.
• Conflicts with main. These 13 files conflict:
  • the two compile-parity receipts;
  • release_input_coverage_manifest.json;
  • target_reference_membership.json;
  • contract.py and its test;
  • uk_spine.json;
  • test_country_spec.py, test_uk_measure_simulation.py, test_uk_national_calibration.py, test_uk_population_targets.py and test_uk_target_references.py.
• Merged without conflict but inconsistent:
  • calibration_measure_exclusions.json: Set UK road-fuel and energy levels in the LCFS stage on a calendar-2024 basis (#1113) #1167 adds four entries and this PR removes three, so the 1,168 count moves.
  • gates.json: regenerate the contract.py digests from the merged file rather than hand-merging them.

Minor

• N3. The reference-person rule moves pensioners' property away from Pension Credit.
  • The FRS reference person is the householder with the highest income, not necessarily the owner of the other property. Pension-age parents living in a household headed by their adult child now record none; it lands on a working-age unit, where Pension Credit never reads it and UC may.
  • The receipts show Pension Credit property on pension-age units falling by roughly £53bn, while design Pension Credit moves only +£0.03bn.
  • It's a consequence of the ruling, not a bug, but it belongs in the D3 signed-difference draft.
• N4. Sentinel units no longer match recorded units.
  • Units on the −1 sentinel stay on the engine's pro-rata proxies at 100% of gross.
  • The Pension Credit proxy doesn't subtract recorded figures, so a pension-age sentinel unit living with a recording reference person counts the property twice.
  • The engine test's mixed recorded/sentinel case was deleted rather than replaced, and the docstring covers UC only.
  • The population is tiny, but the test is worth keeping.
• N5. The £1 refusal in T2 is absolute, while the engine computes in float32 (measure_simulation.py:755-756). For very high-pay salary-sacrifice earners, float32 rounding approaches that size, so a correct schedule could stop the build. It fails closed and passes on the current arms. Add a tolerance of a few float32 steps on top of the £1.
• N6. Merge order with UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 on W is a semantic collision git won't flag. UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 empties the register and pins it empty. If UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 lands first, this PR inherits an empty register with its cell over the bound, and uk_target_fit fails. The description notes the deletion but not that consequence.
• N7. Recorded property still overstates countable capital. By the receipts' own WAS figures it's about 64% of gross after debt, against the 90% recorded. The only tracking is pe-uk#1969, which is the engine side, so a microcosm issue for the WAS mortgage draw would keep it visible.
• Nits.
  • dataset_period sits outside the RulesEngine Protocol (microcosm-frame/rules.py:80-92).
  • The declared dataset_year_rule: survey_year is never resolved; the code uses uk_time_period(frame).
  • _refresh_landlord_carrier silently skips a missing column (spi_income.py:2118-2119), the same pattern as D1.

[vahid-ahmadi]

Thanks María, reviewed at a50ffba5e. Verdict: the "no new release" claim holds on the locked policyengine-uk 2.123.0, and the ports do what #1095 asked. Nothing in the code blocks this from my side once CI is green and 1 is settled. 2 is a record fix, and 3 and 4 are small.

1. Disclosure: exact unweighted counts for small groups in the receipts (experiments/1095-uk-data-ports-3-receipts.md).

   • Around lines 67, 119-123, 131-133, 184-186, 262-263, 305-306 and 408-410, the file gives exact counts of survey records or benefit units for small subpopulations: looked-after children, the reg 8 and mixed-age classes, UC reporters pushed over £16,000, and reporters keeping their receipt. Several fall in the 10-29 band.
   • Line 67 also pairs an exact total with "fewer than 10 of them", which narrows the remainder by differencing. Line 120 pairs an exact unit count with its weighted total, which gives the mean weight per record.
   • They pass the file's own rule (cells under 10 suppressed). But UK local: rerun the 2025 Autumn Budget constituency analysis on the local candidate to find data gaps and per-seat support before Budget day #1241 publishes support counts only as <10, 10–29 or 30+, and this repo is public. The description repeats some of them (the D5 departure note, and the D3 bullets under "What the measurement changed" and "This head").
   • Could you band them before merge? GitHub keeps the description's edit history and the branch's commits, so it may also be worth asking whoever owns UK local: rerun the 2025 Autumn Budget constituency analysis on the local candidate to find data gaps and per-seat support before Budget day #1241 whether anything more is needed.

2. D3 is complete for Universal Credit only after a bump, and the description doesn't say so.

   • On 2.123.0, uc_reported_capital is not in policyengine_uk/data/uprating_indices.yaml, so the dataset projection holds it flat. D3 now puts property into it, so UC assesses property at survey-year values in 2025 and every later year. pension_credit_reported_capital, other_residential_property_value, non_residential_property_value and owned_land all project by GDP per head. So in any year after the survey year, the same property counts at a lower value for UC than for Pension Credit.
   • Your changelog fragment says this (changelog.d/1095-recorded-capital-property.fixed.md:15). But the title and the "Left for later" list don't, and the fix needs an engine release: pe-uk#2201, released in 2.124.0, adds uc_reported_capital to the projection map ("where it used to be held flat").
   • Suggest: add it to "Left for later" and to UK: track the defects uk-data is fixing that microcosm still has #1095's next-bump item, with a note that the D3 receipts at 2025 (units over the UC limit through property) will move at that bump. 2.124.0 also adds benunit_reported_capital, but D3 writes two different figures (land for Pension Credit only, and the UC reporter rule), so microcosm should keep writing both columns directly.

3. One "fix in microcosm now" item from UK: track the defects uk-data is fixing that microcosm still has #1095 isn't in the description. uk-data#547 (no child aged 9-11 months reaches the working-parent entitlement) is in neither the covered list nor "Left for later", and I couldn't find an issue tracking it. It needs a ruling first, so it's fine to leave out, but one line saying so would stop the next UK: track the defects uk-data is fixing that microcosm still has #1095 audit from reading "every actionable item" as covering it. Everything else in that section is covered, listed as later, or in its own PR (Weight UK BRMA assignment by census private-rented households #1087, Map FRS EMPSTATI 11 to OTHER_INACTIVE and refuse unknown adult codes (uk-data#526 parity) #1097, UK: source the extended-hours usage draw from DfE additional-hours PTEs (#1126) #1127, UK scorecard: populace_uk_2023 vs enhanced_frs_2024_25 vs admin benchmarks (2026) #731, and UK landlords: bind the SPI net property amounts, leave property_wealth to the engine, add receipts and finance costs #1145 for property_wealth).

4. Minor: added text cites policyengine-uk 2.122.2, but the lock is 2.123.0. There are 12 added lines across 9 files, including the signed registers: uc_capital_coherence.py:77, frs_take_up.py:52, the D3 changelog fragment, source_stages.json, spec/sources.yaml, take_up_contract.json, test_uk_frs_stochastic.py and the parity fixture. I checked what they describe against 2.123.0 and it's the same, so this is wording only. The next UK: track the defects uk-data is fixing that microcosm still has #1095 audit reads these strings, though, so it's worth making them match the lock.

What I checked

• The no-release claim. uv.lock is unchanged at policyengine-uk 2.123.0. I downloaded the 2.123.0 wheel from PyPI and checked each engine variable and parameter path named in the added code: all 32 variables and all 7 parameter paths exist there. I also read the semantics each port relies on there:
  • is_uc_eligible (D2);
  • the uc_is_in_gainful_self_employment default formula (D1);
  • is_looked_after_by_local_authority and its readers (D5);
  • the UC and Pension Credit capital sources lists and both reported-capital docstrings (D3);
  • earned_income_tax, the schedule on earned_taxable_income by pays_scottish_income_tax that the T2 allocation re-implements;
  • uprating_indices.yaml, which projects savings_interest_income by GDP per head, as T5 assumes, even though the variable's own uprating attribute names household interest.
• UK: track the defects uk-data is fixing that microcosm still has #1095 against the diff. Each port matches its item, including the latent PIP daily-living rows (T6) and the CGT landlord signal (D6). The departures are the ones the description names.
• Tests. Fresh uv venvs, with Hugging Face offline and no private data read.
  • Engine-free tests in the 28 touched files: 1,135 passed, 10 skipped (pinned feed or SPI donor not staged).
  • The same test files on base 977ac983a: 37 fail and 8 files don't import (the D3 and reporter-redraw tests among them), so the new tests pin the changes.
  • The touched engine/uk tests on 2.123.0: 31 passed.
  • ruff check and ruff format --check are clean on the 67 Python files, and tools/ci_test_plan.py verify passes.
• CI and status. The PR left draft this morning, and CI was still pending on this head when I looked.

[juaristi22]

Thanks Vahid. All four are done at a23ddcd64.

1. Disclosure: banded. The receipts and the description now give counts of survey records for small groups only as <10, 10–29 or 30+, as UK local: rerun the 2025 Autumn Budget constituency analysis on the local candidate to find data gaps and per-seat support before Budget day #1241 does.
   • The pairs you named are gone: the total beside "fewer than 10 of them", and the unit count beside its weighted total.
   • One thing more than you asked: the looked-after children are 10–29 child records, but they sit in fewer than 10 survey households. So their weighted totals are removed too.
   • The edit history and the earlier commits are with María.
2. D3 and the engine projection: stated. The D3 summary, "Left for later" and the D3 changelog fragment now say that uc_reported_capital stays at survey-year values on 2.123.0, that 2.124.0 projects it (Record benefit-unit capital once; derive UC and Pension Credit reported capital from it policyengine-uk#2201), and that the D3 figures at 2025 will move at that bump. They also say that the spine keeps writing both columns, for the reason you give.
3. Give children recorded as aged 0 an age in months policyengine-uk-data#547: named as not covered. María ruled on 9 October that the fix belongs in policyengine-uk, whose childcare test should read age in months. No issue is filed for it yet.
4. Engine version: fixed. The lines this PR adds cite the locked 2.123.0, and the rendered stages and the H2 fixture are regenerated. One exception by design: the UC take-up citation was re-signed on 9 October against 2.122.2, so it keeps that fact and adds that 2.123.0 is the same.

Separately, the rebase turned up a defect on main, outside this PR: the release-blocking gate uk_ledger_compile_parity_production_2023 would fail at the next release cut, because the certifier drops the compile's list of unresolved references. The fix is draft #1257.