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Certify the Microcosm UK national from microcosm#1428 on policyengine-uk 2.164.2 (0a4c8e2c; local area 6528c865 or c9df4b86) - #731
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…e2c national, 6528c865 local area) One certify-data run: the national microcosm-uk-2024-25-national-20261031T181401Z-0a4c8e2c certifies on its own build (policyengine-uk 2.164.2); the local-area cut microcosm-uk-2024-25-dense-20261027T154955Z-6528c865 routes on the accepted model mismatch, with its input surface re-audited for 2.164.2 (no dropped column; five inputs added after 2.162.12 take their defaults). Also the relock, the release lock, the TROs, the certified test constants and the changelog fragment. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
PE_UPDATE_SNAPSHOTS=1. The UK households and the model surface move with the model; the US snapshots are unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Property income rates +2pp: what moved, and how it compares with the OBR's income tax line Edited 1 Nov after Max's review: compared with the OBR's income tax line rather than the Table 6.1 total, and the partnership rescale is withdrawn. The table splits the measure's 2029-30 yield into its two parts:
Measures and setup are as in the body's table: the dashboard's measure, policyengine-uk 2.162.14, change in income tax in £bn.
What moved: the relief part.
Against the OBR's income tax line.
Partnership property income: a lead, not a quantified gap.
Bringing it in.
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Thanks María. You've added gross receipts to the national data, and we now estimate a £148m trading allowance cost in 2028-29.
Could we compare the savings and property estimates with the OBR's income tax lines before publishing them? Since 28 October, we've compared each estimate with the OBR line that covers what we model. We keep Table 6.1 totals as context, as we do in Tables 6 and 7 of the briefing. You use Table 6.1 totals in the Official column.
| Measure | Year | This cut | OBR line | This cut against that line | Table 6.1 total |
|---|---|---|---|---|---|
| Savings income rates | 2029-30 | +582 | +443 | exceeds by 31% | +520 |
| 2030-31 | +611 | +475 | exceeds by 29% | +555 | |
| 2031-32 | +636 | +510 | exceeds by 25% | +590 | |
| Property income rates | 2029-30 | +402 | +394 | exceeds by 2% | +435 |
| 2030-31 | +417 | +403 | exceeds by 3% | +445 | |
| 2031-32 | +429 | +412 | exceeds by 4% | +455 | |
| Trading allowance | 2028-29 | −148 | −221 | trails by 33% | −225 |
| 2029-30 | −149 | −165 | trails by 10% | −165 | |
| 2030-31 | −148 | −171 | trails by 14% | −175 | |
| 2031-32 | −147 | −178 | trails by 17% | −180 |
Figures in £ million. We compare savings and property with income tax (measures 62 and 61), and the trading allowance with income tax plus NICs (measure 15).
For savings in 2029-30, the OBR reports £443m of income tax and £78m of onshore corporation tax, £521m in all, and the Treasury rounds that to £520m. You report a scaled £521m, which matches that total and exceeds the income tax line by £78m, or 18%.
In EFO paragraph 3.17, the OBR estimates that savers reduce the yield by around £0.2bn a year, mainly by using tax-advantaged assets such as ISAs. Could you drop "leaves little room for the costing's ISA shifting" and "ISA shifting then looks small"? If we add all £0.2bn to 2029-30 income tax, our £582m would trail the roughly £640m static estimate by about 10%. But the OBR gives no split of the reduction by tax or year, so we can't derive a static income tax line.
We need a verified reason for the 2029-30 and 2030-31 savings gaps before publishing, since both exceed our 25% bar. Our 2031-32 estimate exceeds the income tax line by 24.7%. Could you revise "Why savings sits above the costing" and #1428's savings lines against the income tax lines?
For property in 2029-30, the OBR reports £394m of income tax and £39m across onshore corporation tax and two Scottish lines. The Treasury rounds the £433m total to £435m. You report a rescaled £434m, which exceeds the income tax line by 10%; our published £429m exceeds it by 9%. The OBR estimates that landlords reduce the yield by £0.1bn a year through incorporation and non-compliance. We can use your PRIS bounds to investigate missing partnership income, but we can't quantify any omission from the rescale.
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Thanks @MaxGhenis, agreed on all four points. The model covers income tax, and income tax plus NICs for the trading allowance, so those are the right lines to compare with. Could you verify the savings reading? I'd like your check on whether the savers' response really drives most of the gap, before we rely on it. The evidence is below. What I can't verify is how the OBR's response splits by tax. Savings. Against the income tax line we sit 31%, 29% and 25% above. That compares our static figure with a line after behaviour.
Property.
Trading allowance.
Revised:
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Thanks María. The OBR and the government publish no static costing by tax in the policy table, the EFO or the costing note, so we can't settle "at least half" from published figures. The OBR estimates that savers cut the yield by around £0.2bn a year across taxes, while we hold savers' choices fixed.
The government leaves ISA returns out of the costing's tax base (costing, p.75), so savers moving into ISAs cut the income tax line. The OBR also scores keeping the cash ISA limit at £20,000 on income tax alone, about −£35m in 2029-30 (policy table, measure 11), and the government gives that measure "no static impact" (costing, p.19). Neither of them sizes the income tax loss from ISA shifting under the savings rise, or splits its effects across taxes. Neither the OBR nor the government explains the £78m of corporation tax, which starts at +£13m in 2026-27, before the rates rise.
Your £0.75bn includes that corporation tax, so we can compare our estimates with the OBR's income tax line plus an assumed response on income tax:
| Assumed response on income tax, each year | Implied static income tax, 2029-30 to 2031-32 | Our estimates |
|---|---|---|
| £75m | £518m, £550m, £585m | exceed it by 12%, 11% and 9% |
| £150m | £593m, £625m, £660m | trail it by 2%, 2% and 4% |
| £200m | £643m, £675m, £710m | trail it by 9%, 9% and 10% |
| £250m | £693m, £725m, £760m | trail it by 16%, 16% and 16% |
About £70m a year on income tax would cover half of the gap, and about £140m all of it. At least £23m a year would bring our excess under 25% in all three years. Your review of PolicyEngine/microcosm#1428 also finds that our model includes annuity and trust income in the savings measure's base (finding 1). Our estimates and these amounts can move with the rebuild.
The government grows the 2023-24 SPI base "using the OBR's forecast for growth in savings income" (costing, p.75), but it doesn't say whether that growth applies before the frozen allowances. If the static income tax line trailed ours by 13%, the income tax response would come to about £63m, £57m and £43m, under a third of the OBR's £0.2bn. Neither the OBR nor the government publishes enough detail to rule out those amounts.
The OBR counts Self Assessment receipts in its line, and we count liabilities. Taxpayers who make payments on account normally base them on an earlier bill and settle the balance later, so growing savings liabilities can widen the gap from 2029-30 too.
Could you replace "So the gap reads as at least half behaviour, and probably most of it" in the PR with "The OBR estimates that savers cut the yield by around £0.2bn a year across taxes. It publishes no split by tax or year, so we can't yet say how much of the gap that response explains"? Could you also drop "matters only before 2029-30"?
For the trading allowance, could you replace the sentence beginning "The rest is" with "The government includes traders switching to the allowance in its costing but doesn't quantify that response. This scoring engine also doesn't relieve miscellaneous income (PolicyEngine/policyengine-uk#2726)"?
I'll come back on the bar and on whether we can get the split from the OBR, and we'll keep savings off the dashboard until then.
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Review of 6b2d0b9 Max's three requested edits are all in the body: his savings sentence replaces "at least half behaviour", "matters only before 2029-30" is gone, and the trading allowance sentence is his. The two ISA phrases from his first review are gone too. I don't repeat his points below, and I leave the (a)/(b) local-area choice to him. Must
Should
Nits
Arithmetic checked, no slips: savings 31/29/25% (2031-32 is 24.7%), property 2/3/4%, trading allowance 10-17% from 2029-30 (33% in 2028-29), #728's 30-33% and 31-36% and 6-8%, Carer's Allowance 92.5% and 91.3% of Table 6.1 (#728 about 40%), electricity 4% and 9% (#728 11% and 16%), and the relief decomposition (rate plus relief equals yield within £1m rounding; £14m and £20m of £27m). CI: Verdict: pins and certified constants are consistent; the open question is item 1, which the body should state before this leaves draft. What I checked: the body against both of Max's reviews; the diff: H5 sha256 Not verified: the H5 contents and HF manifests (private data, not downloaded); the scores themselves; the snapshot values; the UC floor receipt. No local build or test run. 🤖 Generated with Claude Code |
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The cash ISA limit and the Machine Games Duty rise on this national (Budget 2026, Table 6.1 rows 11 and 56) Measured on Cash ISA limit kept at £20,000 (row 11)
Machine Games Duty: 20% to 25% on machines with a stake above £1 or a prize above £100 (row 56)
Measure 56 also carries the supplier-liability change from 2028-29: +20, +15, +15 and +10 in the costing note. Table 6.1 combines the two in one row: +135, +150, +145, +145, +145. The higher-stake share.
DisclosureWeighted national totals and shares only. Every figure rests on well over 10 source households. 🤖 Generated with Claude Code |
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Follow-up on 6b2d0b9 The head, title and body are as they were at my review this morning (the body was last edited on 1 Nov at 16:52), so all of its items are still open:
On the cash ISA and Machine Games Duty comment (11:03) The sourced figures check out:
Should
Nit
Verdict: the 11:03 figures are sound and the method is stated honestly. Nothing in it changes the PR; item 1 is still the one to settle before this leaves draft. CI: What I checked: the PR body, title, edit history and timeline since my review; the 11:03 comment against Table 6.1 and the policy costing note (both in uk-autumn-budget-dashboard-2026 Not verified: the cut's own figures (8.2m payers, 33%, £18.5bn, the £3.11bn base, the ISA scores); the Gambling Commission and HMRC statistics behind 75.7%, 75.4%, 76.4% and 88.6%; HMRC's 22%; SI 2026/1018; the 10.6% growth (Table 4.10 has no 2024-25 column); the Bank Rate and deposit rate paths; the 75–90% back-out. 🤖 Generated with Claude Code |
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Cash ISA limit kept at £20,000 (row 11): what decides the taxed share, and how to treat the excess cc @vahid-ahmadi. This follows up the measurements above. No official source gives the share of the excess that would have been taxed. The survey evidence and the OBR's own figures narrow it enough to choose a treatment, and the interest rate matters as much as the share. The evidence
What each treatment gives on this nationalIncome tax, Budget against pre-Budget law, £m. The engine (policyengine-uk 2.164.2) runs on the households holding an under-65 cash ISA saver above £12,000, which is exact for income tax.
The proposed treatment
Weighted national totals only. Every figure rests on well over 10 source households. 🤖 Generated with Claude Code |
@MaxGhenis, for the UK hub: this certifies the national from PolicyEngine/microcosm#1428 on policyengine-uk 2.164.2 and supersedes #728. It needs the same decision from you as #728: which local-area cut it keeps, (a) or (b) below. That call carries over from #728, and this PR stays a draft until you make it.
The national
microcosm-uk-2024-25-national-20261031T181401Z-0a4c8e2c(microcosm_uk_2024_25):a8e25870cwith policyengine-uk 2.164.2, so it certifies on its own build (built_with_model_package). The core stays 3.33.3, withcore_binding: bundle_pinas on main.f8543876415f47819f56094c71ca4dab4cad6dcb2ba3a13b97f6982e38444c9e.--no-latest, tag only) on 1 Nov at 11:09 UTC; not promoted.The local area: your call
Constituency and local-authority regions route to the local-area cut (
regional_release_kind: local_area). Neither cut below carries the fixes in PolicyEngine/microcosm#1419, PolicyEngine/microcosm#1420 or PolicyEngine/microcosm#1428, so area runs don't see them. The next rebuilt pair will.(a) #725's
microcosm-uk-2024-25-dense-20261027T154955Z-6528c865. This draft's default.b71ce793, the head of Settle property allowance elections without the charge where it cannot change them policyengine-uk#2695, labelled 2.162.12.(b) main's
microcosm-uk-2024-25-dense-20261026T105309Z-c9df4b86, the local-area data the dashboard reads today.--audited-by juaristi22) and a limitation saying the cut was built on 2.151.0. Its H5 is on hand and matches the manifest pin, and the audit takes about a minute.is_apprentice. Area runs on it would read them as zero, along with the five inputs (a) defaults, so they would carry no alcohol, tobacco or gambling duty.If you choose (b), I'll run the audit, re-certify and push it here.
Before the dashboard moves to this bundle
other_investment_incomein market and HBAI income. On this pin, household net income carries the tax on that income without the income itself. Costings read tax and benefits, so the table below is unaffected.Budget measures on this national
Scored with #728's method: the PolicyEngine/uk-autumn-budget-dashboard-2026 measures (
57095fd) and their October 2026 forecast. Each figure is the weighted change ingov_balance, in £bn. They were scored on policyengine-uk 2.162.14, as #728's table was; the bundle pins 2.164.2, and a rescore there can follow.Columns:
0a4c8e2c, from SPI donor savings rebased to SPI's 2023-24 bands (savings follow-up to #1418) microcosm#1428.4374e0bf.a6299504with 2.151.0.(1) The dashboard's State Pension template wraps
income_tax, which on policyengine-uk 2.162.x adds the Winter Fuel Payment charge, so the template refuses. The port is the dashboard's to do; the data play no part (#728, note 1).What moved against #728's national:
Savings against the OBR's income tax line
Edited after Max's review, which compares the savings rates with the OBR's income tax line rather than the Table 6.1 total. That total adds £78m of onshore corporation tax in 2029-30, which the model doesn't cover. The earlier reading here is withdrawn: a difference of base level, with ISA shifting small.
Impact
Commits
59662673: the national and the local area, certified by onecertify-datarun. It also has the lock, the release lock, the TROs, the certified test constants and the changelog fragment.6b2d0b9f: the household calculator snapshots, regenerated on 2.164.2 (PE_UPDATE_SNAPSHOTS=1). The UK households and the model surface move with the model; the US snapshots don't change.How it was made
uk_qualification.rewrite_certified_constantsrewrote the certified constants intests/test_models.py,tests/test_release_manifests.pyandtests/test_uk_regions.py.Evidence run on this head
The UC floor passed (
check_uk_uc_floor.py, Great Britain, 2025, within 10%). The receipt holds weighted national totals only:It took 119 s and peaked at 8.2 GB.
Both
bundle.py checkruns pass, the second with--include-tros --strict-tros.Locally, 435 tests pass on the release manifests, UK regions, models, household snapshots, UC floor, bundle, TRO, certification, regional-evidence, pin and release-lock paths. The full suite runs in CI.
Disclosure
Aggregates only: weighted national totals over many records, and published HMRC, ONS, DWP, OBR and Treasury figures.
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