[juaristi22]

Part of #1095. This PR collects the #1095 items that pass their measurement, and since 31 October the Phase B items too. Each item is measured in its own national build against the one before it. Every figure that rests on the SPI channel is given as a class only (SN 9422 and the disclosure rule).

A/B items (measured against the 28 October build, then against the 2 November control):

1. The SPI stage-1 forests train and query on the SPI age band (uk-data#628).
2. Households' additional-dwelling (HRAD) purchases at or below £250,000 are allocated from HMRC's Table 8a receipts.
3. Drawn SPI employees' current pay is floored at what their twin's hours earn, and the tape's pay stays their year of pay (uk-data#629).

Phase B items (each measured against the build before it):

• B5: Carer's Allowance claims are drawn after salary sacrifice, keyed on lineage.
• B12: Scottish owners' council tax bands are drawn from their council area's band mix.
• AC3: the two-child-limit rows date births by the engine's cutoff test.
• B7: children in non-parental care are marked for the two-child limit's exception.
• B10: SPI copies take their twin's contributory JSA and ESA within the permitted-work limit.
• B9: each household's student-loan balance moves to its borrowers.

Phase B items that change nothing in the build:

• B6 (ages from the interview): dropped, by María's ruling of 2 November. The stored ages already sit at the engine's reference date (note).
• B8 (benefit-cap exemptions): every exemption the engine reads is already set. The engine's own gaps are in Lift the Universal Credit benefit cap for a claimant who receives War Widow's Pension policyengine-uk#2792 and Add Guardian's Allowance policyengine-uk#174.

Also since the first review:

• Vahid's five points of 29 October, each in its own commit (reply):
  • the one-hot SPI age band;
  • the pay floor's receipt on the floor of 3;
  • paid_hours;
  • the UC gate's pools;
  • the HRAD docstring.
• The UC take-up gate is back at 0.055 for each family type, by María's ruling of 2 November (follow-up).

How the items were measured

• Control: María's national build of 2 November, cut f6e33b93 at SPI donor savings rebased to SPI's 2023-24 bands (savings follow-up to #1418) #1428's 329a99e71 (policyengine-uk 2.165.1, feed 08962f1b), staged on populace-uk-private.

• T1426: this branch with the A/B items and Vahid's fixes, built on this machine with the control's review date (2 November) and feed.

  • Its 17 stages before the SPI income stage give the same evidence and records as the control's. So the two machines' inputs agree.

• Phase B: one build per group of items, in a chain: B-1 against T1426, B-2 against B-1, B-3 against B-2. All use the same review date, feed and lock, and all 1,339 rows are active in every build.

• Main merged in: the branch now merges main at 312dc4d6b, which adds SPI donor savings rebased to SPI's 2023-24 bands (savings follow-up to #1418) #1428's last commit (2dbf7cf, SPI banding on total income net of expenses). A control rebuilt on main and this branch's merged tree measure the whole PR on the current base (below).

• Control (f6e33b93): 98.5% of rows within 10%, final loss 0.00529.

• T1426 (A/B items and Vahid's fixes):

  • 98.8% within 10%, final loss 0.00527.
  • 21 rows move more than 5 points, all HMRC SPI regional and income-band rows. That is reseed-sized: a placebo that only reseeded the SPI stage moved 22.

• B-1 (B5): 98.8% within 10%, final loss 0.00527. No row moves.

• B-2 (AC3, B7): 98.7% within 10%, final loss 0.00532. No row moves more than 5 points.

• B-3 (B10, B9): 98.7% within 10%, final loss 0.00522. No row moves more than 5 points.

• Control on main (ctl-312d):

  • 98.7% within 10%, final loss 0.00539.
  • Its 17 stages before the SPI income stage give the same evidence and records as the control's; from that stage on it differs, as main's SPI banding commit should.
  • Against the control, 10 rows move more than 5 points, all HMRC income-band and regional rows.

• This branch merged with main (t1426m):

  • 98.7% within 10%, final loss 0.00520.
  • Against the control on main, by stage:
    • Its stages before the SPI income stage give the same evidence and records, except frs_relationships (B7).
    • From the SPI income stage on, every stage's evidence differs, as this branch's SPI items should.
    • The stage order differs only where B5 moves the Carer's Allowance stage.
  • Against the control on main, by row:
    • 14 rows move more than 5 points, all HMRC income-band and regional rows. That is fewer than the 22 a reseed-only placebo moved.
    • Before calibration, obr.jobseekers_allowance's shortfall halves (B10).
    • After calibration, dwp.esa_claimants comes inside 10%. The UC households-by-children rows stay near the 10% line, as they do in both controls.

Every build passes every spine gate and all seven calibration gates.

1. The SPI stage-1 forests on the SPI age band (uk-data#628)

Why

The 2022-23 SPI public-use tape gives age only as a band (AGERANGE). The SPI income stage drew an age for each donor inside its band and trained the stage-1 tape forest on it, so the forest learned no real income pattern within a band. Twins of one band were then drawn from conditionals that differed only by that noise. uk-data#628 reports the same defect in uk-data.

What changes

• The stage-1 tape and reference forests read the SPI age band, one-hot, instead of age (Vahid's review). On the tape it is the AGERANGE code, with composite records (-1) as a band of their own. On a frame person it is the band of their whole-year age, through one helper shared by both frames.
• at_or_over_spa still carries the State Pension split inside the 65-74 band.
• The cross-fit fold cells key on the band.
• The drawn donor ages stay on the donor for their other readers: the band pools' State Pension side and the property components' tape seed.

Measurement

• Against the 28 October build, the item moved no more rows than a draw-seed placebo, and the UC rows ended closer to DWP's.
• The copies' pay now rises with age inside the youngest bands nearly as FRS employees' does, and falls with age over 55 as theirs does. The placebo changed none of this.

2. Households' HRAD at or below £250,000 from Table 8a receipts

Why

The property purchases stage (#1308, porting uk-data#573) allocates households' HRAD purchases by individuals' share of all Table 8a residential transactions (0.881) and value (0.882). #1308's review found this probably overstates households' purchases.

The residential nil-rate band was £250,000 for all of 2024-25. A purchase at or below it owes no standard-rate SDLT, so other buyers' receipts in that band are surcharge.

What changes

• The nil-rate band from receipts: households' HRAD at or below £250,000 is Table 6b's band less other buyers' HRAD implied by their Table 8a receipts. The stage refuses an implied figure outside Table 6b's band or above other buyers' own transactions there.
• Above the band, uk-data#573's shares stay. Solving for other buyers' HRAD from receipts goes negative above £1m. The module docstring says the shares probably still overstate households' purchases. Table 8a doesn't split out the 2% non-resident surcharge, so the nil-band figure, if anything, understates them (Vahid's review).
• Targets: households' 2024-25 HRAD target falls from 186,589 transactions and £68.81bn to 151,928 and £63.71bn.

All figures in this section are HMRC's published Annual Stamp Tax Statistics 2024 to 2025, Tables 6b and 8a, as the pinned feed carries them.

Measurement

Households' purchases fit their new target, and no row moved by more than 5 points against the 28 October build. obr.sdlt fits within 0.25% after calibration in every build.

3. Drawn SPI employees' current pay at their twin's hours (uk-data#629)

Why

The SPI income stage keeps each drawn copy's FRS twin's hours and job, while stage 1 redraws the copy's pay from the 2022-23 tape. The tape's pay covers the tax year and holds part-year workers, so part-year pay could land on a current full-time twin, at an hourly rate far below the minimum wage. Such a copy fails the minimum-income tests of the 30 hours' childcare offer, Tax-Free Childcare and the benefit cap more often than the FRS rows it copies.

What changes

• The floor: floor_spi_employment_pay_at_minimum_wage lifts a drawn copy's pay to its twin's usual weekly paid hours (paid_hours, Vahid's review) × 52 × the lower of the minimum wage for the twin's age and the twin's own hourly pay.
• Who it touches: only drawn recipients other than reserved band carriers, whose twin has an employee main job, no trade and usual hours, and whose drawn pay is positive. FRS rows are never modified.
• The tape's year of pay: the floored pay is current pay only. employment_income_annual_share keeps the HMRC income rows on the tape's pay.
• Receipt: an employment_pay_floor receipt and an hourly-pay check. A figure resting on one or two source households is withheld as "<3", on the shared floor of 3 (Vahid's review).
• Gate: uk_stage_hmrc_spi_income_spine_hourly_pay refuses a spine where an eligible copy stays below its floor, or where drawn employees sit below the minimum wage more often than FRS employees by more than two points.
• The UC take-up gate is at 0.055 again for each family type and for the reachable pools (María's ruling of 2 November). With SPI donor savings rebased to SPI's 2023-24 bands (savings follow-up to #1418) #1428's pool joining, every family type ends closer to DWP's count after the redraw.

Measurement

After the floor, drawn employees sit below the minimum wage for their age less often than FRS employees, within the gate's margin, and no eligible row stays below its floor. The HMRC employment-income bands end as without the floor, since their annual measures read the tape's pay.

B5: Carer's Allowance after salary sacrifice

• What changes: the Carer's Allowance take-up stage runs after salary_sacrifice, so its earnings test reads pay after sacrifice. That puts it after the CGT copies, so its draws are keyed on lineage: a copy draws as the member it copies, and a source and its copies in one stratum count as one record of their joint weight. Original rows keep their draws.
• Measurement (B-1 against T1426):
  • Only the Carer's Allowance stage differs, and every calibration row is unchanged.
  • The change turns off the claim flag only on CGT copies that salary sacrifice puts over the earnings limit, and the engine already paid them nothing.
  • So it makes the flag consistent with what the engine pays.

B12: Scottish owners' council tax bands

• What changes: Scottish owners' bands are drawn, at the same uniform, from their council area's chargeable-dwellings mix (Scottish Government, September 2025, A to H), vendored from the pinned feed as uk/scotgov_chargeable_dwellings_by_band.json. Renters and the per-copy bill stay with the bill-level issue.
• Measurement: it runs only in dense builds, so the national builds here can't measure it. It is measured in the next dense build.

AC3: two-child-limit births by the engine's cutoff test

• What changes: the 15 two-child-limit rows read the engine's uc_is_child_born_before_child_limit (a date of birth before 6 April 2017) instead of a birth year of 2017 or later. A child born from January to 5 April 2017 no longer counts as affected.
• Measurement (B-2): the seven rows whose measure reads the cutoff start 1% to 4% lower, and all 15 still fit within 0.5%.

B7: non-parental care and the two-child limit

• What changes: frs_relationships sets child_limit_non_parental_caring_exception for a child whom no adult of their own benefit unit claims as a natural, adopted or step child (household grid codes 3 and 4 from the child, 7 and 8 from the adult), and whom no local authority placed there. This covers kinship and friends care.
  • Multiple births stay at the engine's default: the FRS has no twin field, and its birth dates are blank (María's ruling of 2 November).
  • The flag leaves the signed engine-default register.
• Measurement (B-2): inert in this build. The flag reaches the calibrated dataset, but no flagged child is a third or later child born after the cutoff in a paid UC claim, so no row moves.

B10: SPI copies' contributory JSA and ESA within the permitted-work limit

• Why: spi_benefit_coherence zeroed contributory JSA on every SPI copy and left contributory ESA with the stage-2 forest's draw, which knows nothing of the unit's claim history. A contributory award follows the person's National Insurance record and incapacity, which the copy keeps; what the copy changes is its work.
• What changes:
  • An SPI copy takes its FRS twin's contributory JSA and ESA where its own earnings stay within ESA's permitted-work limit, and none above it (María's ruling of 29 October). The earnings are employment income plus any self-employment profit, over 52 weeks.
  • The limit is policyengine-uk's own esa_exempt_work_higher_earnings_limit at the frame's year, £183.50 a week in 2024-25.
  • The new operation is in the source manifest and the sources schema.
  • The stage gate checks the rule on every copy, and contributory ESA leaves the QRF tail-concentration surface, since no forest draw survives in it.
• Measurement (B-3 against B-2):
  • On the copies, contributory ESA falls (the forest had given them more than their twins report) and contributory JSA returns at a small level.
  • Before calibration, obr.jobseekers_allowance's shortfall halves. The ESA rows start further below DWP's and OBR's: without the forest's extra ESA, the FRS base's own shortfall shows.
  • All of them fit after calibration, and dwp.esa_claimants comes inside 10%.

B9: student-loan balances to borrowers

• Why: was_wealth splits the household's WAS student-loan balance before any plan exists, so it could sit on a member with no loan while the household's borrower held none. policyengine-uk caps a borrower's repayment at a positive balance.
• What changes: once student_loans sets the plans, each household's balance moves to its members who hold one: by repayments where any of them repays, equally otherwise. A household with no borrower keeps was_wealth's split, and no household's total moves. The stage opens a reader-isolation boundary in the UK graph, since it rewrites a cell an earlier open-surface stage reads.
• Measurement (B-3): the SLC repayment rows' starting estimates move by under 1%, and they all fit after calibration. Their large starting overshoot is not the balance's: the WAS balance is a small part of SLC's loan book, so few repayments are capped.

Tests

JUnit counts on the merged tree (2b49a00):

• Engine-free: 351 files in 30-file chunks, 13,226 tests, 125 skipped.
  • Two tests fail, both only on this machine: one expects the UK extra to be absent, and the Orrery reconstruction test meets a local Node error.
• Engine tier: 101 tests, none failing:
  • H2 parity and the full graph admission;
  • SPI income and the permitted-work limit;
  • the UK graph, its terminal gates and the full target graph;
  • release input coverage and the concept mapping.
• Generated surfaces:
  • The H2 parity fixture regenerates byte-identically.
  • The release input coverage manifest, the CI test plan and the spec-engine coverage are current.

New and changed test files, against main:

• New: tests/engine/uk/test_uk_spi_permitted_work_limit.py reads the permitted-work limit from policyengine-uk at 2024 and 2025.
• Engine tier: test_uk_spi_income.py.
• Engine-free, UK:
  • test_uk_carers_allowance_take_up.py, test_uk_frs_relationships.py and test_uk_property_localisation.py;
  • test_uk_property_purchases.py, test_uk_source_stages.py and test_uk_spi_benefit_coherence.py;
  • test_uk_spi_income.py, test_uk_spi_pension_age.py, test_uk_spi_rank_transport.py and test_uk_spi_spine.py;
  • test_uk_spine_acceptance_receipt.py, test_uk_stage_health.py and test_uk_student_loans.py;
  • test_uk_uc_capital_coherence.py, test_uk_uc_target_measurements.py and test_uk_weighted_integrity.py.
• Engine-free, shared: test_country_spec.py, and microcosm-data's test_contract.py.
• Test support: uk_atomic_support_fixtures.py and uk_student_loans.py.

Follow-up

• B4, the HICBC liability target: HMRC's count of Self Assessment taxpayers with a liability, and the charge's revenue, are already in the pinned feed (Child Benefit statistics, August 2025, Table 16). The target's definition is María's call.
• Phase B builds still to run: B-4 (the gambling stake level), B-5 (PR 2b, the NTS vehicle file) and B-6 (copy ids re-keyed). The target-side items B11, B14 and B15 follow them.
• NS4 (benefit-cap support): still on a thin base. The repair options are an SPI-channel rule for copies' cap state (UK SPI channel after #840: residuals, post-merge measurements and stale pointers #1288) or a support stage.
• uk-data#573 still allocates every band by the shares. Raising this there is María's call.

Generated surfaces: source_stages.json (in step with sources.yaml), the sources schema, the release input coverage manifest, the H2 parity fixture, and the gate digests mirrored in microcosm-data's contract.

🤖 Generated with Claude Code

[vahid-ahmadi]

@juaristi22 thanks, this is my review of 457af0274.

Verdict: the three items look sound, with four should items and a nit. The age band is the right fix for #628. The nil-band arithmetic reproduces the body's numbers: £265m over £625m/113,500 is about 48,100 transactions, and the target falls by about 34,700. The pay floor runs where it should, after stage 1 and the uprating and before employment_income, stage 2 and pension coherence, with the twin cap and the kept year of pay. Nothing here blocks the A/B arms.

Findings

1. should: composites (-1) sit next to 16-24 on an ordinal predictor. spi_age_band is numeric, not one of SPI_STAGE1_CATEGORICAL_PREDICTORS (spi_income.py:2252, 2623). So any split above -1 that doesn't separate -1 from 1 puts composite records in the leaves 16-24 queries land in. Before, composites drew an age across 16-70, so they spread over every band. Now they can only mix with the youngest one, and composites are the tape's high-income amalgams. Please either keep composites out of the stage-1 training set, one-hot the band, or check on the arm that 16-24 draws' top tail is not higher than on main. A line in the predictor rule saying which would do.
2. should: the new floor receipt hardcodes ten. spi_income.py:936, 940, 951-952 and 961 use < 10 and "<10", and the gate docstring says "fewer than ten" (stage_health.py:1425). UK: take up #1095's actionable items on policyengine-uk 2.165.1 #1422 moves every UK floor onto receipt_counts.UK_DISCLOSURE_FLOOR. Whichever lands second should move these onto the constant and the helpers (small_cell_share, rounded_count), or this receipt will be the only one still on ten. The gate's "a withheld share is not judged" branch then follows too.
3. should: one tolerance loosens two checks. uk_stage_uc_take_up goes from 0.055 to 0.12 (gates.json:633). That widens the "no further from DWP than before the redraw" leg, which the floor needs. But the same number bounds the reachable pools, which the notes say realize DWP's count within 0.0015. A second parameter for the pools, left at 0.055 or tighter, would keep that check meaningful while the other is wide. Please also name the issue that tracks the return to 0.055, so the revert isn't left to memory.
4. should (a question): does Table 8a's nil-band receipts figure for other buyers include the 2% non-resident surcharge? If it does, part of those receipts is not HRAD surcharge. Then other buyers' implied HRAD is too high and households' too low (property_purchases.py:473). The direction is the safe one, and it may be small. One sentence in the module docstring saying which way it goes would do.
5. nit: paid_weeks (spi_income.py:893) is annual paid hours (hours / 52 * 52), not weeks. paid_hours would read better.

What I ran. I read the full diff at 457af0274 and checked the HRAD figures by hand. I also checked that the SPI leaf reconciliation runs on the donor tape, before the floor, so the floor can't break it. CI is green at this head. I didn't run tests locally or build anything, and I didn't check the private A/B figures.

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[juaristi22]

@vahid-ahmadi thanks for the review. All five points are addressed. #1422 has landed, and main is merged in at bc7f59aac.

1. Composites next to 16-24: the age band is now one of the stage-1 categorical predictors, one-hot encoded with gender, region and main source, so composite records are a category of their own (dae46ae94). The predictor rule, the spec's categorical list and the changelog say so. The next build re-measures the three items with it.
2. The floor receipt's ten: the receipt withholds through UK_DISCLOSURE_FLOOR and UK_WITHHELD ("<3"). Its descriptions, the hourly-pay gate's note and docstring, and its tests follow (f1092f14c). Two test cases shrink their small side to two households, so they still test the withholding, and the engine test's floored households read "3-9" (8f0ec8fd7). UK: take up #1095's actionable items on policyengine-uk 2.165.1 #1422's floor guards pass on the merged tree.
3. One tolerance, two checks: the reachable pools keep their own maximum_reachable_pool_deviation at 0.055, beside maximum_caseload_deviation at 0.12 (d68eb5cbb). The caseload check returns to 0.055 when UK: every open data item: uk-data parity, engine locks, the local surface, consumption and high-value homes #1095's UC award item ("UC awards below the top band are too low") lands, per María's ruling of 29 October.
4. Table 8a and the non-resident surcharge: HMRC's commentary does not say whether Table 8a's receipts include it. HRAD makes up more than half of the residential receipts it reports, so they read as whole SDLT receipts. The module docstring now says which way the surcharge goes: read as HRAD surcharge, it raises other buyers' implied HRAD and lowers households', so households' nil-band purchases are, if anything, understated (f3d9c0af0).
5. paid_weeks: renamed paid_hours (bc5adc97c).

The H2 fixture is regenerated on the merged tree (bc7f59aac). The full UK engine tier passed locally before main's merge, and CI runs it on the merge. #1095's Phase B joins this PR next (María's call of 31 October). Each item is measured against the national control built from #1428 at 329a99e71 (cut f6e33b93), on policyengine-uk 2.165.1, the lock main and #1428 share.

[juaristi22]

@vahid-ahmadi a follow-up on point 3: #1428 is now merged in at the control's commit, and on the T1426 spine every family type ends closer to DWP's count after the take-up redraw than before it. So the caseload check is back at 0.055 (0ddc23673, María's ruling of 2 November), and nothing is left to track. The pools keep their own maximum_reachable_pool_deviation, also at 0.055.

[vahid-ahmadi]

@juaristi22 Round 2 at 2b49a00ac. I re-checked my five points from 457af0274, read your two replies, and read the Phase B diff against main (312dc4d6b): B5, B7, AC3, B9, B10 and B12. I checked B10 and B7 against the legislation. I ran the PR's engine-free tests for the stages it touches (spi_benefit_coherence, student_loans, frs_relationships, carers_allowance_take_up, stage_health, property_localisation, uc_target_measurements): 281 passed. I didn't build anything or look at the private figures.

Earlier points

1. Composites next to 16-24: fixed. spi_age_band is the first of SPI_STAGE1_CATEGORICAL_PREDICTORS (spi_income.py:185-190), so _encode_predictor_frames one-hots it. Tape and query codes are both float, so their dummy columns match (spi_income.py:2663, 3028-3030). The query side never produces -1, so the composite column is always 0 for frame people, as it should be.
2. The floor receipt's ten: fixed. It now uses UK_DISCLOSURE_FLOOR/UK_WITHHELD throughout (spi_income.py:984-1042).
3. One tolerance, two checks: fixed. maximum_reachable_pool_deviation is separate (stage_health.py:1542-1546, 1586) and both values are 0.055 (gates.json:655-656). See below on your follow-up.
4. Non-resident surcharge: fixed. The module docstring says which way it goes (property_purchases.py:39-44).
5. paid_weeks: fixed, now paid_hours (spi_income.py:939).

On your point-3 follow-up. I agree the caseload check can go back to 0.055 and nothing is left to track. One caveat on where the evidence comes from. The gate note cites the T1426 spine at 97fd4d0e4 (gates.json:658). That merges #1428 at 329a99e71, before #1428's SPI banding commit 2dbf7cf56, so the "every family type ends closer after the redraw" reading was taken on the old SPI stage. The body says B-1 to B-3 and t1426m all pass every spine gate, so the 0.055 gate has also passed on the current base. Please name t1426m's commit in the gate note next to 97fd4d0e4, since that is the spine the gate now runs on. If the receipt shows how far inside 0.055 the closest family type sits on t1426m, one figure there would also help. The body already says the T1426 and B-chain A/B measurements were taken against the pre-2dbf7cf56 control, and that ctl-312d/t1426m measure the PR on the current base, so I have nothing to add there.

New findings

1. Should: B10 gives contributory JSA ESA's permitted-work limit, which is about twice JSA's own earnings limit (spi_benefit_coherence.py:517-530). Contribution-based JSA needs the claimant's earnings not to exceed the prescribed amount (Jobseekers Act 1995 s.2(1)(c); JSA Regs 1996 reg 56: the age-related amount plus the earnings disregard, less 1p). For a claimant aged 25 or over in 2024-25 that is £90.50 + £5 − £0.01 = £95.49 a week. Below that, s.4(1)(b) reduces the award by earnings above the disregard. Failure case: an SPI copy aged 30 earning £7,800 a year (£150 a week), whose twin reports £4,706 of contributory JSA (£90.50 × 52), keeps all £4,706 at this head. Under the law it would get nothing, because £150 is above £95.49. At £50 a week it keeps £4,706 where the award would be about £2,366 a year (£45.50 a week). The docstring says the ESA limit is only a ceiling for JSA (spi_benefit_coherence.py:66-68). But the body puts part of the halving of obr.jobseekers_allowance's pre-calibration shortfall down to B10, so the gap matters here. Fix: test jsa_contrib_reported against reg 56's amount at the copy's age (the engine's JSA age-related amount + £5), and either reduce the award by earnings above £5 or zero it above the prescribed amount. Or, if María keeps the ESA limit for both, have the receipt report the copies' weighted JSA between £95.49 and £183.50 a week, so the JSA row's movement can be read with that in mind.
2. Nit: B10's "the test reads no hours" doesn't quite hold. spi_benefit_coherence.py:66 says the SPI tape has no hours. But the copy carries its twin's usual hours, which the pay floor reads (SPI_EMPLOYMENT_PAY_FLOOR_HOURS_COLUMN). ESA reg 45(4) also needs fewer than 16 hours a week. Either test the hours too, or reword the docstring to say why the twin's hours aren't used.
3. Nit: B7's flag is an upper bound on the legal exception (frs_relationships.py:204-218). UC Regs 2013 Sch 12 para 4(2) (before its revocation from 6 April 2026) needs a friend or family carer to meet one of conditions (a) to (h): a child arrangements order, special guardianship, guardian's allowance, a kinship care order, guardianship, a permanence order, or taking the child on where they would otherwise likely be looked after. The FRS grid shows none of these. So every child with no parent or step-parent in their benefit unit is flagged, including informal arrangements that wouldn't qualify. It is inert in this build, so one line in the rule's comment calling it an upper bound would do.

Checked and fine

• B5: lineage_roots refuses an unmapped or duplicated lineage. Originals keep their person_id draws. lineage_balanced_positions treats a source and its copies in one stratum as one record, and the within-one-record assert is widened to match.
• B9: allocate_balance_to_borrowers keeps each household's total (with a hard check), leaves households with no borrower or no balance alone, and splits by repayments, or equally where nobody repays.
• AC3: the measure now reads uc_is_child_born_before_child_limit, so a January to 5 April 2017 birth no longer counts as affected.
• B10 limit: 16 × £11.44 = £183.04, rounded up to £183.50 (ESA Regs 2008 reg 45(4) and (9A)), which matches the test constant.
• B12: the loader refuses a council area missing a band or repeating one, Northern Ireland and renters keep their bands, and the Scottish receipt is separate.

CI at 2b49a00ac: all ten checks pass (engine-free and engine-uk on 3.13 and 3.14, engine-us, integration-uk, lint, wheels).

Verdict: my earlier points are all fixed and I agree with the 0.055 return. B10's JSA limit is the one item to settle before the JSA row's movement is quoted.

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