[juaristi22]

Fixes #2168.

Employer National Insurance reforms can change wages and other household incidence
channels, so their gross NI yield and net government balance answer different questions.
The existing parameter descriptions do not explain those assumptions or how to control
them.

This documentation expands the three incidence parameters and their README, adds an
Assumptions page, and refreshes the worked household comparison after the secondary
threshold correction in #2165. It explains the earnings-input route, the residual
consumer and capital channels, the three-zero control, and how to match an official
costing's definition. Parameter values, dates and formulas are unchanged. No empirical
justification or preferred incidence default is claimed.

axiom: n/a: Documentation and descriptive metadata only; no policy values, eligibility rules or calculated model behaviour change.

Validation:

• Ten existing employer-NI incidence YAML cases passed. Their source and calculation semantics are unchanged.
• The page's four household scenarios ran before editing and again from the finished code block; all four reproduced, including the post-construction earnings override.
• Jupyter Book 2 / MyST HTML build passed, including the new page and its navigation. The first sandbox DNS failure is retained; the successful retry downloaded the builder's public theme/web assets locally.
• make format passed with 1,495 Python files unchanged. Parsed parameter values, dates, units and labels are unchanged, as are 1,769 protected model/test files.

Local validation used Python 3.13.14, core 3.32.27 and Hypothesis 6.168.2; the lockfile specifies core 3.33.2 and Hypothesis 6.169.0. Hosted CI will check the locked environment. No representative population estimate or empirical default calibration was run.

[juaristi22]

Formatted the page’s Python fence in c9375f6 to resolve the Lint failure. The example’s AST, surrounding prose, other five authored files and 1,769 protected model/test files are unchanged.

All five local lint/guard checks pass with pinned Ruff 0.17.0, and independent verification is CLEAN. New-head hosted CI is pending.

[vahid-ahmadi]

Fine once the parameter descriptions are shortened.

@juaristi22, the page is accurate. I checked each claim about the mechanism against the code and reran the worked example. The points below are about where the text lives and two small source details.

1. should: policyengine_uk/parameters/gov/contrib/policyengine/employer_ni/employee_incidence.yaml:2, consumer_incidence.yaml:2, capital_incidence.yaml:2. Each description is now a paragraph of 70 to 90 words. It mentions holders, Simulation construction and dataset attributes. This field is the text users see for the parameter in the app, and the sibling exempt_employer_pension_contributions.yaml keeps one sentence. Please cut each to one sentence, for example "Share of the fixed-employer-cost pay change passed to employees in the same year; set all three incidence parameters to 0 to disable these channels." The README and the new page already carry the detail.
2. nit: docs/book/assumptions/employer-ni-incidence.md:186 cites OBR paragraph 2.14 for the roughly 60% pass-through, but #2168 quotes the same wording from Box 2.1. The OBR site blocked my download, so I could not check which is right. Please confirm the location. Secondary sources also describe the OBR's 60% as going to "workers and consumers, via lower wages and higher prices", not to employees alone. A check of the exact wording would be worth it.
3. nit: the page and README use US spellings ("modeled", "modeling", "labor") at employer-ni-incidence.md:20,43,57,71 and README.md:5,17. Most of docs/book uses British spelling.
4. nit: the issue also asked the page to say when the default is the better headline. The PR body says no preferred default is claimed, which is a fair choice. If that is the intent, a short sentence on the page would close that point of the issue.
5. nit: the parameter reference entries point at this repo's own code. That is honest, as there is no external source, but it might read better as a note in the description or README than as a legal reference.

What I checked

• Read the full diff and #2168.
• Read employer_ni_fixed_employer_cost_change.py, both residual-incidence formulas, household_tax.py, household_net_income.py and simulation.py:350. Each statement about guards, the below-threshold rule, household_tax inclusion, exclusion from gov_tax and the constructor remapping matches the code.
• Ran the page's code block from a fresh venv at head c9375f6a. All four rows reproduce to the penny: +301.72 / −60.34 / −24.14 / −301.72 / +217.24 / −217.24, then +350.00 with zeros for the other three rows. Both residual channels return 0 in every row.
• Hand-checked the first row: £45,250 baseline cost, (45,250 + 0.16 × 5,000) / 1.16 = £39,698.28, so −£301.72 in pay. 20% and 8% of that give the tax and NI rows.
• The secondary-threshold parameter is stored as 5,000 / 52, so the £5,000 in the text is right.
• policyengine-core test policyengine_uk/tests/policy/baseline/contrib/policyengine/employer_ni -c policyengine_uk: 10 passed.
• The new page is picked up by the docs/book/assumptions/*.md pattern in myst.yml. The README's relative link resolves.
• Hosted CI on head c9375f6a: all checks pass, including Test / Python 1-4, YAML, Lint and both docs builds. The fragment type changed fits a docs-only change, and the body has an axiom: n/a line.
• No clash with other open PRs that I found. #2386 adds other pages under docs/book/assumptions/ but no shared files.
• Could not check: the OBR EFO text itself (blocked download), and any population run.

🤖 Generated with Claude Code

[juaristi22]

Addressed item 1 in f72a29b: all three parameter descriptions are now single sentences and explain how to disable the incidence channels.

Values, dates, defaults and references are unchanged. After rebasing onto main at 7ad002f, the parameter-description test and all 10 employer-NI YAML cases passed, along with Ruff and the PR evidence check.

[github-actions]

Aggregate impact on certified data: pass

Base ee92a51d12 against head 8af612677a, both on enhanced_frs_2024_25.h5 (policyengine-uk-data 1.58.1, sha256 056e80fd8e91), fiscal years 2025-26 to 2031-32. Each year is a full microsimulation run on each side.

Checks: 0 broken by this change, 1 failing on both sides, 0 fixed. Moves flagged for review: 0 (thresholds in report_spec.yaml; a flag does not fail the job).

Workflow run and full report

Notes

• In the years a figure from fewer than 10 records is suppressed (spending.disabled_students_allowance), every total containing it, and the decile incomes, are rebuilt from their other components, so no published total includes it. Those totals are marked †. A change is withheld where the two sides leave out different figures and can't be lined up.

Moves flagged for review

None.

Spending by benefit and service

Measure	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Disabled Students' Allowance	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed

Caseloads

Measure	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Disabled Students' Allowance	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed

Household net income by decile

No household's net income changes in any year.

No change in any year: receipts by tax head; government balance, each component counted once; model totals; components the model counts twice; household income totals; population; poverty rates; people in poverty; inequality; mean household net income in each side's own deciles; standard reform costings (change in gov_balance); standard reforms: change in each reform's target.

Checks failing on both base and head (1)

• VAT is never negative (sign:vat): 2025-26: 76 units below zero, a weighted £-54,797,972 in total; 2026-27: 76 units below zero, a weighted £-56,271,349 in total; 2027-28: 76 units below zero, a weighted £-57,609,146 in total

Counted-once check

Each of 84 components was raised by £1 per unit in 2026-27, and every head of its totals was read household by household: its own head must rise by exactly £1, no other tax head may move, no other benefit may rise, and the model's own total must move by what its heads moved. A head that breaks a rule is measured again twice: with every other head held at its baseline value, and with every other head held at its value after the first £1 while the component rises again. It fails where either still shows the response. 0 failed; 0 were skipped.

• incapacity_benefit: pension_credit responds only through other heads in fewer than 10 households (other heads that moved there: carers_allowance; gov_spending; not a failure)
• incapacity_benefit: pension_credit responds only through other heads in fewer than 10 households (other heads that moved there: carers_allowance; household_benefits; not a failure)
• incapacity_benefit: universal_credit responds only through other heads in 72 households (other heads that moved there: carers_allowance, carer_support_payment; gov_spending; not a failure)
• incapacity_benefit: universal_credit responds only through other heads in 72 households (other heads that moved there: carers_allowance, carer_support_payment; household_benefits; not a failure)
• maternity_allowance: pension_credit responds only through other heads in fewer than 10 households (other heads that moved there: carers_allowance; gov_spending; not a failure)
• maternity_allowance: pension_credit responds only through other heads in fewer than 10 households (other heads that moved there: carers_allowance; household_benefits; not a failure)
• declared double count corporate_sdlt is still contained in expected_sdlt (coefficient 1.000; Corporate SDLT is counted twice in household and government tax totals #2159)

Provenance

Side	Commit	Runtime	Environment hash	Partition hash	Time
base	main ee92a51d12	uk 2.136.0, core 3.33.2, py 3.13.16 aarch64	0f7814ad5bd9	0d0426ee9e38	894.23s
head	#2469 merged into main 8af612677a	uk 2.136.0, core 3.33.2, py 3.13.16 aarch64	0f7814ad5bd9	0d0426ee9e38	895.75s

Dataset: hf://policyengine/policyengine-uk-data-private/enhanced_frs_2024_25.h5@2526edbbb687a3b54dbb11272e5389e4b62d2ac2, sha256 056e80fd8e9151d78f432a25cde863340baee81304c6216a37fb575ce8563784 (verified on both sides), policyengine-uk-data 1.58.1.

Receipts by tax head: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Income tax	£298.30bn	£318.11bn	£335.36bn	£350.32bn	£365.75bn	£383.77bn	£402.05bn
National Insurance (employee and self-employed)	£52.58bn	£54.94bn	£56.75bn	£58.48bn	£60.51bn	£62.45bn	£64.90bn
National Insurance (employer)	£152.64bn	£159.18bn	£164.14bn	£168.73bn	£175.57bn	£181.08bn	£188.22bn
Employer NI change borne by capital	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Employer NI change borne by consumers	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Capital gains tax	£12.62bn	£13.06bn	£13.55bn	£14.04bn	£14.54bn	£15.09bn	£15.65bn
Student loan repayments	£7.83bn	£8.12bn	£8.35bn	£8.56bn	£8.79bn	£9.04bn	£9.38bn
VAT	£253.71bn	£260.53bn	£266.72bn	£273.14bn	£279.83bn	£286.71bn	£293.71bn
Change in VAT from its baseline	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
VAT on private school fees	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Fuel duties	£24.53bn	£24.64bn	£26.64bn	£26.69bn	£26.42bn	£25.76bn	£26.35bn
Alcohol duties	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Tobacco duties	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Vehicle excise duties	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
TV licence fee	£4.28bn	£4.43bn	£4.44bn	£4.46bn	£4.49bn	£4.51bn	£4.53bn
Council tax	£49.56bn	£52.45bn	£55.78bn	£59.39bn	£62.98bn	£66.74bn	£70.70bn
High value council tax surcharge	£0.00bn	£0.00bn	£0.00bn	£0.48bn	£0.50bn	£0.51bn	£0.52bn
Northern Ireland domestic rates	£0.55bn	£0.58bn	£0.61bn	£0.63bn	£0.67bn	£0.70bn	£0.73bn
Business rates	£31.73bn	£31.73bn	£31.73bn	£31.73bn	£31.73bn	£31.73bn	£31.73bn
Stamp duty land tax (own purchases, and corporate until the	£10.26bn	£10.84bn	£11.32bn	£11.80bn	£12.29bn	£12.83bn	£13.42bn
Land transaction tax (Wales)	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.01bn	£0.01bn
Land and buildings transaction tax (Scotland)	£0.01bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn
Unspecified tax change borne by capital	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Unspecified tax change borne by consumers	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Wealth tax	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Wealth tax excluding the main residence	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Land value tax	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Carbon tax	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn

Spending by benefit and service: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
State Pension	£122.50bn	£127.12bn	£128.28bn	£130.21bn	£134.05bn	£138.02bn	£142.08bn
Pension Credit	£6.68bn	£7.06bn	£7.04bn	£7.11bn	£7.23bn	£7.37bn	£7.46bn
Winter Fuel Payment	£1.70bn	£1.68bn	£1.59bn	£1.57bn	£1.57bn	£1.55bn	£1.52bn
Pension Age Winter Heating Payment (Scotland)	£0.19bn	£0.20bn	£0.20bn	£0.21bn	£0.21bn	£0.22bn	£0.22bn
Universal Credit	£79.17bn	£83.50bn	£85.32bn	£87.08bn	£88.02bn	£89.45bn	£90.80bn
Housing Benefit	£8.60bn	£8.93bn	£9.20bn	£9.34bn	£9.62bn	£9.88bn	£10.17bn
Council Tax Reduction	£1.99bn	£2.03bn	£2.08bn	£2.13bn	£2.18bn	£2.24bn	£2.29bn
Employment and Support Allowance (income-related)	£2.12bn	£2.18bn	£2.23bn	£2.28bn	£2.33bn	£2.39bn	£2.45bn
Employment and Support Allowance (contribution-based)	£5.22bn	£5.36bn	£5.49bn	£5.62bn	£5.76bn	£5.90bn	£6.04bn
Jobseeker's Allowance (income-based)	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Jobseeker's Allowance (contribution-based)	£0.29bn	£0.30bn	£0.30bn	£0.31bn	£0.32bn	£0.33bn	£0.33bn
Income Support	£0.12bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Working Tax Credit	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Child Tax Credit	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Incapacity Benefit	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Personal Independence Payment	£27.05bn	£28.19bn	£28.94bn	£29.64bn	£30.37bn	£31.11bn	£31.87bn
Disability Living Allowance	£7.52bn	£7.83bn	£8.04bn	£8.24bn	£8.44bn	£8.65bn	£8.86bn
Attendance Allowance	£8.71bn	£9.08bn	£9.32bn	£9.55bn	£9.78bn	£10.02bn	£10.26bn
Carer's Allowance	£4.50bn	£4.69bn	£4.81bn	£4.93bn	£5.05bn	£5.17bn	£5.29bn
Carer Support Payment (Scotland)	£0.35bn	£0.37bn	£0.38bn	£0.39bn	£0.40bn	£0.41bn	£0.41bn
Carer's Allowance Supplement (Scotland)	£0.00bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn
Severe Disablement Allowance	£0.03bn	£0.03bn	£0.03bn	£0.03bn	£0.03bn	£0.03bn	£0.03bn
Industrial Injuries Disablement Benefit	£0.51bn	£0.52bn	£0.53bn	£0.54bn	£0.56bn	£0.57bn	£0.59bn
Armed Forces Compensation Scheme	£0.61bn	£0.62bn	£0.64bn	£0.65bn	£0.67bn	£0.69bn	£0.70bn
War Widow's or Widower's Pension	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Child Benefit	£16.23bn	£16.91bn	£17.32bn	£17.73bn	£18.16bn	£18.60bn	£19.04bn
Scottish Child Payment	£0.50bn	£0.52bn	£0.53bn	£0.55bn	£0.56bn	£0.57bn	£0.58bn
Two Child Limit Payment (Scotland, counterfactual)	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Healthy Start vouchers	£0.05bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn	£0.05bn
Maternity Allowance	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Statutory Maternity Pay	£3.32bn	£3.41bn	£3.49bn	£3.57bn	£3.66bn	£3.75bn	£3.84bn
Statutory Paternity Pay	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Statutory Sick Pay	£1.13bn	£1.16bn	£1.19bn	£1.22bn	£1.25bn	£1.28bn	£1.31bn
Sure Start Maternity Grant	£0.01bn	£0.01bn	£0.01bn	£0.01bn	£0.01bn	£0.01bn	£0.01bn
Bereavement Support Payment	£0.67bn	£0.69bn	£0.70bn	£0.72bn	£0.74bn	£0.76bn	£0.78bn
Tax-Free Childcare	£0.55bn	£0.56bn	£0.57bn	£0.58bn	£0.60bn	£0.61bn	£0.59bn
Extended childcare entitlement	£2.65bn	£3.09bn	£3.17bn	£3.24bn	£3.33bn	£3.41bn	£3.49bn
Universal childcare entitlement	£3.27bn	£3.39bn	£3.48bn	£3.57bn	£3.66bn	£3.77bn	£3.85bn
Targeted childcare entitlement	£0.57bn	£0.59bn	£0.61bn	£0.62bn	£0.64bn	£0.66bn	£0.66bn
Care to Learn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Childcare Grant	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Parents' Learning Allowance	£0.20bn	£0.20bn	£0.20bn	£0.20bn	£0.20bn	£0.20bn	£0.20bn
Adult Dependants' Grant	£0.06bn	£0.06bn	£0.04bn	£0.04bn	£0.04bn	£0.04bn	£0.04bn
Travel Grant	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Disabled Students' Allowance	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed
16 to 19 Bursary Fund	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
NHS spending	£204.68bn	£205.46bn	£206.22bn	£207.04bn	£207.96bn	£208.89bn	£209.79bn
State education spending	£0.02bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn	£0.02bn
Transport subsidy spending	£25.15bn	£25.25bn	£25.34bn	£25.44bn	£25.55bn	£25.67bn	£25.78bn
Cost-of-living support payment	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Energy Bills Rebate	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Energy Price Guarantee subsidy	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Basic income	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Disability basic income	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn
Other public spending budget change	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn

Caseloads: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
State Pension	11,308k	11,208k	10,906k	10,812k	10,860k	10,908k	10,955k
Pension Credit	1,491k	1,489k	1,477k	1,455k	1,457k	1,454k	1,451k
Winter Fuel Payment	7,091k	7,008k	6,593k	6,509k	6,491k	6,377k	6,242k
Pension Age Winter Heating Payment (Scotland)	806k	807k	807k	805k	809k	812k	816k
Universal Credit	6,372k	6,379k	6,409k	6,420k	6,395k	6,387k	6,371k
Housing Benefit	1,254k	1,253k	1,254k	1,240k	1,245k	1,247k	1,249k
Council Tax Reduction	3,187k	3,212k	3,225k	3,247k	3,263k	3,282k	3,296k
Employment and Support Allowance (income-related)	187k	188k	188k	189k	190k	190k	191k
Employment and Support Allowance (contribution-based)	722k	724k	727k	730k	733k	737k	740k
Jobseeker's Allowance (income-based)	0k	0k	0k	0k	0k	0k	0k
Jobseeker's Allowance (contribution-based)	67k	67k	68k	68k	68k	69k	69k
Income Support	25k	0k	0k	0k	0k	0k	0k
Working Tax Credit	0k	0k	0k	0k	0k	0k	0k
Child Tax Credit	0k	0k	0k	0k	0k	0k	0k
Incapacity Benefit	0k	0k	0k	0k	0k	0k	0k
Personal Independence Payment	3,581k	3,595k	3,608k	3,623k	3,639k	3,655k	3,671k
Disability Living Allowance	1,296k	1,301k	1,306k	1,311k	1,317k	1,323k	1,329k
Attendance Allowance	1,701k	1,708k	1,714k	1,721k	1,729k	1,736k	1,744k
Carer's Allowance	1,038k	1,042k	1,046k	1,050k	1,055k	1,059k	1,064k
Carer Support Payment (Scotland)	81k	82k	82k	82k	83k	83k	83k
Carer's Allowance Supplement (Scotland)	0k	82k	82k	82k	83k	83k	83k
Severe Disablement Allowance	4k	4k	4k	4k	4k	4k	4k
Industrial Injuries Disablement Benefit	137k	138k	139k	139k	140k	140k	141k
Armed Forces Compensation Scheme	94k	94k	94k	95k	95k	95k	96k
War Widow's or Widower's Pension	0k	0k	0k	0k	0k	0k	0k
Child Benefit	8,136k	8,165k	8,185k	8,215k	8,249k	8,282k	8,314k
Scottish Child Payment	352k	354k	355k	356k	357k	358k	357k
Two Child Limit Payment (Scotland, counterfactual)	0k	0k	0k	0k	0k	0k	0k
Healthy Start vouchers	200k	201k	202k	203k	204k	204k	205k
Maternity Allowance	0k	0k	0k	0k	0k	0k	0k
Statutory Maternity Pay	334k	335k	336k	338k	339k	341k	342k
Statutory Paternity Pay	0k	0k	0k	0k	0k	0k	0k
Statutory Sick Pay	182k	183k	183k	184k	185k	186k	186k
Sure Start Maternity Grant	26k	26k	26k	27k	27k	27k	27k
Bereavement Support Payment	98k	98k	99k	99k	100k	100k	101k
Tax-Free Childcare	1,017k	1,028k	1,028k	1,033k	1,034k	1,038k	1,023k
Extended childcare entitlement	665k	671k	675k	677k	682k	686k	687k
Universal childcare entitlement	986k	989k	992k	997k	1,002k	1,013k	1,015k
Targeted childcare entitlement	119k	120k	120k	121k	121k	122k	121k
Care to Learn	0k	0k	0k	0k	0k	0k	0k
Childcare Grant	0k	0k	0k	0k	0k	0k	0k
Parents' Learning Allowance	98k	99k	99k	100k	100k	100k	101k
Adult Dependants' Grant	18k	18k	12k	13k	13k	13k	13k
Travel Grant	0k	0k	0k	0k	0k	0k	0k
Disabled Students' Allowance	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed	suppressed
16 to 19 Bursary Fund	0k	0k	0k	0k	0k	0k	0k
Cost-of-living support payment	0k	0k	0k	0k	0k	0k	0k
Energy Bills Rebate	0k	0k	0k	0k	0k	0k	0k
Energy Price Guarantee subsidy	0k	0k	0k	0k	0k	0k	0k
Basic income	0k	0k	0k	0k	0k	0k	0k
Disability basic income	0k	0k	0k	0k	0k	0k	0k

Government balance, each component counted once: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Government receipts, each component once	£898.60bn	£938.62bn	£975.41bn	£1,008.49bn	£1,044.08bn	£1,080.93bn	£1,121.92bn
Government spending	£536.94bn †	£551.10bn †	£557.43bn †	£564.51bn †	£573.07bn †	£582.33bn †	£591.49bn †
Government balance, each receipt once	£361.67bn †	£387.52bn †	£417.98bn †	£443.98bn †	£471.01bn †	£498.60bn †	£530.43bn †
Benefits in household_benefits but not in gov_spending	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn	£0.00bn

Model totals: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
gov_tax	£901.73bn	£941.75bn	£978.54bn	£1,011.62bn	£1,047.21bn	£1,084.06bn	£1,125.05bn
household_tax	£495.38bn	£522.04bn	£547.68bn	£569.74bn	£591.81bn	£616.26bn	£643.12bn
pre_budget_change_household_tax	£487.56bn	£513.92bn	£539.33bn	£560.70bn	£582.53bn	£606.72bn	£633.22bn
gov_spending	£536.94bn †	£551.10bn †	£557.43bn †	£564.51bn †	£573.07bn †	£582.33bn †	£591.49bn †
household_benefits	£536.94bn †	£551.10bn †	£557.43bn †	£564.51bn †	£573.07bn †	£582.33bn †	£591.49bn †
gov_balance	£364.80bn †	£390.65bn †	£421.11bn †	£447.11bn †	£474.14bn †	£501.73bn †	£533.56bn †

Components the model counts twice: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
corporate_sdlt, counted again inside expected_sdlt	£3.13bn	£3.13bn	£3.13bn	£3.13bn	£3.13bn	£3.13bn	£3.13bn

Household income totals: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Household market income	£1,657.06bn	£1,719.25bn	£1,771.68bn	£1,821.99bn	£1,887.41bn	£1,945.59bn	£2,017.37bn
Household net income	£1,659.34bn †	£1,707.55bn †	£1,739.55bn †	£1,773.81bn †	£1,810.06bn †	£1,851.71bn †	£1,903.31bn †
Household net income (HBAI definition)	£1,468.17bn	£1,514.88bn	£1,547.36bn	£1,580.55bn	£1,614.82bn	£1,654.01bn	£1,704.49bn

Population: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
People	69,514k	69,778k	70,036k	70,316k	70,626k	70,944k	71,249k
Benefit units	35,247k	35,381k	35,512k	35,654k	35,811k	35,972k	36,127k
Households	31,167k	31,285k	31,401k	31,526k	31,665k	31,808k	31,944k

Poverty rates: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Absolute poverty, before housing costs: everyone	15.9%	14.9%	15.5%	15.6%	15.7%	15.8%	15.7%
Absolute poverty, before housing costs: children	23.7%	20.9%	21.6%	21.4%	21.6%	21.8%	21.7%
Absolute poverty, before housing costs: working-age adults	13.8%	13.4%	14.0%	14.1%	14.2%	14.3%	14.3%
Absolute poverty, before housing costs: pensioners	13.6%	13.1%	13.2%	13.4%	13.5%	13.6%	13.5%
Absolute poverty, after housing costs: everyone	20.9%	20.4%	21.0%	21.2%	21.4%	21.7%	21.8%
Absolute poverty, after housing costs: children	31.8%	30.0%	30.7%	31.0%	31.2%	31.6%	31.8%
Absolute poverty, after housing costs: working-age adults	19.4%	19.2%	20.0%	20.2%	20.5%	20.7%	20.8%
Absolute poverty, after housing costs: pensioners	12.5%	12.2%	12.0%	12.2%	12.2%	12.3%	12.3%
Relative poverty, before housing costs: everyone	17.0%	16.4%	16.5%	16.6%	16.8%	16.8%	16.9%
Relative poverty, before housing costs: children	25.7%	23.5%	23.3%	23.2%	23.4%	23.5%	23.7%
Relative poverty, before housing costs: working-age adults	14.5%	14.4%	14.7%	14.8%	15.1%	15.1%	15.2%
Relative poverty, before housing costs: pensioners	14.8%	14.9%	14.4%	14.4%	14.3%	14.4%	14.6%
Relative poverty, after housing costs: everyone	21.5%	21.1%	21.3%	21.4%	21.5%	21.6%	21.8%
Relative poverty, after housing costs: children	32.6%	31.3%	31.1%	31.1%	31.4%	31.4%	31.8%
Relative poverty, after housing costs: working-age adults	19.8%	19.8%	20.2%	20.3%	20.5%	20.7%	20.8%
Relative poverty, after housing costs: pensioners	13.3%	12.8%	12.6%	12.7%	12.3%	12.2%	12.3%

People in poverty: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Absolute poverty, before housing costs: everyone	11,050k	10,426k	10,847k	10,945k	11,075k	11,205k	11,215k
Absolute poverty, before housing costs: children	3,559k	3,140k	3,260k	3,252k	3,297k	3,333k	3,333k
Absolute poverty, before housing costs: working-age adults	5,864k	5,737k	6,070k	6,164k	6,236k	6,314k	6,319k
Absolute poverty, before housing costs: pensioners	1,627k	1,549k	1,517k	1,528k	1,542k	1,558k	1,563k
Absolute poverty, after housing costs: everyone	14,536k	14,210k	14,688k	14,922k	15,145k	15,380k	15,517k
Absolute poverty, after housing costs: children	4,765k	4,513k	4,641k	4,697k	4,753k	4,831k	4,894k
Absolute poverty, after housing costs: working-age adults	8,275k	8,251k	8,665k	8,836k	8,991k	9,138k	9,200k
Absolute poverty, after housing costs: pensioners	1,496k	1,445k	1,382k	1,389k	1,401k	1,411k	1,423k
Relative poverty, before housing costs: everyone	11,807k	11,456k	11,570k	11,652k	11,832k	11,919k	12,065k
Relative poverty, before housing costs: children	3,863k	3,538k	3,520k	3,528k	3,567k	3,592k	3,642k
Relative poverty, before housing costs: working-age adults	6,178k	6,160k	6,389k	6,483k	6,623k	6,674k	6,741k
Relative poverty, before housing costs: pensioners	1,767k	1,758k	1,661k	1,642k	1,642k	1,653k	1,682k
Relative poverty, after housing costs: everyone	14,918k	14,717k	14,897k	15,056k	15,215k	15,345k	15,518k
Relative poverty, after housing costs: children	4,886k	4,714k	4,695k	4,721k	4,789k	4,814k	4,894k
Relative poverty, after housing costs: working-age adults	8,442k	8,497k	8,756k	8,884k	9,018k	9,123k	9,201k
Relative poverty, after housing costs: pensioners	1,590k	1,507k	1,446k	1,451k	1,408k	1,408k	1,423k

Inequality: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Gini coefficient, equivalised HBAI income before housing costs	0.3076	0.3053	0.3067	0.3074	0.3079	0.3086	0.3096

Mean household net income in each side's own deciles: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Decile 1: mean household_net_income per household	£17,701 †	£17,986 †	£17,930 †	£18,005 †	£18,312 †	£18,507 †	£18,668 †
Decile 2: mean household_net_income per household	£28,345 †	£29,006 †	£28,643 †	£28,959 †	£29,297 †	£29,667 †	£30,264 †
Decile 3: mean household_net_income per household	£34,596 †	£35,840 †	£36,513 †	£36,996 †	£37,351 †	£38,068 †	£38,716 †
Decile 4: mean household_net_income per household	£39,340 †	£40,981 †	£41,875 †	£42,608 †	£43,161 †	£43,755 †	£44,885 †
Decile 5: mean household_net_income per household	£44,541 †	£46,019 †	£46,949 †	£47,578 †	£48,334 †	£49,282 †	£49,907 †
Decile 6: mean household_net_income per household	£48,356 †	£49,451 †	£50,382 †	£51,209 †	£52,330 †	£53,133 †	£54,591 †
Decile 7: mean household_net_income per household	£56,413 †	£57,572 †	£58,474 †	£59,440 †	£60,063 †	£61,464 †	£63,069 †
Decile 8: mean household_net_income per household	£69,292 †	£70,485 †	£71,702 †	£73,027 †	£74,348 †	£75,820 †	£77,601 †
Decile 9: mean household_net_income per household	£79,707 †	£82,059 †	£83,307 †	£84,456 †	£86,255 †	£87,808 †	£90,034 †
Decile 10: mean household_net_income per household	£117,835 †	£120,650 †	£122,572 †	£124,724 †	£127,210 †	£129,846 †	£132,991 †

Standard reform costings (change in gov_balance): head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Raise basic rate by 1pp	£6.22bn	£6.50bn	£6.71bn	£6.90bn	£7.11bn	£7.35bn	£7.62bn
Raise higher rate by 1pp	£3.54bn	£3.82bn	£4.05bn	£4.27bn	£4.49bn	£4.76bn	£4.96bn
Raise personal allowance by ~800GBP/year	£-3.84bn	£-3.98bn	£-4.06bn	£-4.11bn	£-4.20bn	£-4.32bn	£-2.04bn
Raise child benefit by 25GBP/week per additional child	£-2.00bn	£-1.76bn	£-1.64bn	£-1.54bn	£-1.44bn	£-1.34bn	£-1.24bn
Reduce Universal Credit taper rate to 20%	£-20.54bn	£-21.10bn	£-21.45bn	£-21.88bn	£-21.96bn	£-22.33bn	£-22.81bn
Raise Class 1 main employee NICs rate to 10%	£11.06bn	£11.51bn	£11.83bn	£12.14bn	£12.46bn	£12.80bn	£13.27bn
Raise VAT standard rate by 2pp	£25.01bn	£25.68bn	£26.29bn	£26.92bn	£27.58bn	£28.26bn	£28.95bn
Raise additional rate by 3pp	£2.83bn	£3.07bn	£3.26bn	£3.46bn	£3.66bn	£3.89bn	£4.21bn
Raise the Universal Credit standard allowance by 10%	£-3.04bn	£-3.17bn	£-3.25bn	£-3.32bn	£-3.37bn	£-3.43bn	£-3.47bn
Raise the State Pension by 10%	£-8.93bn	£-9.14bn	£-9.06bn	£-9.12bn	£-9.31bn	£-9.55bn	£-9.82bn

Standard reforms: change in each reform's target: head levels

Measure (head)	2025-26	2026-27	2027-28	2028-29	2029-30	2030-31	2031-32
Raise basic rate by 1pp: change in income_tax	£6.36bn	£6.65bn	£6.87bn	£7.07bn	£7.29bn	£7.53bn	£7.81bn
Raise higher rate by 1pp: change in income_tax	£3.54bn	£3.83bn	£4.06bn	£4.28bn	£4.50bn	£4.77bn	£4.97bn
Raise personal allowance by ~800GBP/year: change in income_tax	£-3.97bn	£-4.12bn	£-4.22bn	£-4.27bn	£-4.36bn	£-4.48bn	£-1.79bn
Raise child benefit by 25GBP/week per additional child: change in child_benefit	£2.34bn	£2.15bn	£2.03bn	£1.92bn	£1.82bn	£1.71bn	£1.59bn
Reduce Universal Credit taper rate to 20%: change in universal_credit	£20.53bn	£21.09bn	£21.44bn	£21.87bn	£21.95bn	£22.32bn	£22.80bn
Raise Class 1 main employee NICs rate to 10%: change in national_insurance	£11.33bn	£11.79bn	£12.13bn	£12.44bn	£12.77bn	£13.12bn	£13.61bn
Raise VAT standard rate by 2pp: change in vat	£25.01bn	£25.68bn	£26.29bn	£26.92bn	£27.58bn	£28.26bn	£28.95bn
Raise additional rate by 3pp: change in income_tax	£2.83bn	£3.07bn	£3.26bn	£3.46bn	£3.66bn	£3.89bn	£4.21bn
Raise the Universal Credit standard allowance by 10%: change in universal_credit	£3.04bn	£3.17bn	£3.25bn	£3.32bn	£3.38bn	£3.43bn	£3.48bn
Raise the State Pension by 10%: change in state_pension	£12.25bn	£12.71bn	£12.83bn	£13.02bn	£13.41bn	£13.80bn	£14.21bn

[vahid-ahmadi]

@juaristi22 round 2, at f72a29be5. The branch was rebased, so I compared this PR's own diff before and after. The only change is the three parameter descriptions.

Verdict: the round-1 should is fixed. Approving.

Round-1 points

1. Parameter descriptions: fixed. employee_incidence.yaml, consumer_incidence.yaml and capital_incidence.yaml now have one sentence each, ending with how to switch the channels off. Values, dates, labels and references are unchanged. The detail is still on the new page and in the README.
2. OBR paragraph 2.14 or Box 2.1: still open (nit). The page still cites "paragraph 2.14" (employer-ni-incidence.md:186). Please check this against the EFO before merge if you can.
3. US spellings: still open (nit). "modeled", "labor" and similar are still at employer-ni-incidence.md:20,43,57,71.
4. and 5. Nits on the preferred default and the self-referencing reference entries: unchanged. Both were optional.

No new findings.

What I checked

• Compared the PR's diff at c9375f6a5 with its diff at f72a29be5. Only the three description fields differ.
• Fresh worktree and uv venv at the head. policyengine-core test on tests/policy/baseline/contrib/policyengine/employer_ni: 10 passed. test_parameter_descriptions.py: passed.
• Merges cleanly with current main (8b12bce94) and with #2490. CI at the head: all 16 checks pass, and the aggregate-impact report shows no change.
• Not checked: the OBR EFO text itself.

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