# Data sources ledger

This is the audit trail for every figure baked into `src/data/`. Do **not** trust NHS
pay/tax figures from generic "NHS pay calculator" websites — during research for this
project a whole cluster of near-identical SEO sites (nhstakehome.co.uk,
nhspaybands.org.uk, payslipiq.co.uk, nhspaycalculator.uk/.co.uk,
mynhstakehomecalculator.co.uk, nhstakehomepaycalculator.co.uk, pensionplain.co.uk, etc.)
were found repeating and occasionally *contradicting* each other and the primary
sources. One even stated the 2026/27 personal allowance as £13,000, when it is
frozen at £12,570. Only primary/official sources are used below; secondary
corroboration is noted where used to fill a gap.

| Dataset | Tax year | Value(s) | Source | Retrieved | Notes |
|---|---|---|---|---|---|
| AfC pay scales, England | 2025/26 | Band 2 £24,465 – Band 9 top £125,637 | NHS Employers, "NHS Terms and Conditions 2025 (Agenda for Change)" poster, https://www.nhsemployers.org/system/files/2025-05/2025%20AfC%20pay%20scales.pdf | 2026-07-24 | Primary. Read directly from PDF. |
| AfC pay scales, England | 2026/27 | Band 2 £25,272 – Band 9 top £129,783 | NHS Employers, "NHS Terms and Conditions 2026 (Agenda for Change)" poster, https://www.nhsemployers.org/system/files/2026-02/2026%20AfC%20pay%20scales.pdf | 2026-07-24 | Primary. 3.3% uplift from 2025/26. |
| AfC pay scales, Scotland | 2025/26 & 2026/27 | Full band/point table, Annex B (2025/26) & page 9 (2026/27) | Scottish Government NHS Circular PCS(AFC)2025/5, 19 May 2025, https://www.publications.scot.nhs.uk/files/pcs2025-afc-05.pdf | 2026-07-24 | Primary. Two-year deal: +4.25% (2025/26), +3.75% (2026/27), each subject to a CPI inflation-guarantee top-up announced separately (not modelled here — see risk note below). |
| AfC pay scales, Wales | 2025/26 | Full band/point table, Annex 1 | Welsh Government Pay Letter AfC(W) 02/2025, 29 May 2025, https://www.nhs.wales/files/pc-resources/afc-w-02-2025-pdf-2-pdf/ | 2026-07-24 | Primary. +3.6% uplift from 2024/25. Wales sets its own scale (Band 1/2 floor is Wales-specific Living Wage top-up, not a plain % of England's). |
| AfC pay scales, Wales | 2026/27 | Full band/point table, Annex 1 | Welsh Government Pay Letter AfC(W) 02/2026, 12 February 2026, https://www.nhs.wales/files/pc-resources/afc-w-02-2026-pdf-pdf/ | 2026-07-24 | Primary. +3.3% uplift from 2025/26 (excludes the Living Wage advance payment carve-out noted in the circular). |
| AfC pay scales, Northern Ireland | 2025/26 & 2026/27 | **Approximated as identical to England's AfC scale** | No NI-specific circular could be located; UNISON NI reporting (2026) confirms the Health Minister intends to apply England's 3.3% 2026/27 uplift, and NI/HSC has historically shared England's core AfC pay spine, but implementation is frequently delayed relative to England. | 2026-07-24 | 🚩 **Unverified approximation** — replace with the actual HSC pay circular once published/located. Flagged in-app nowhere yet; flag to the user before relying on NI figures for real pay decisions. |
| HCAS (England only) | 2025/26 (from 1 April 2025) | Inner 20% (min £5,609/max £8,466); Outer 15% (min £4,714/max £5,941); Fringe 5% (min £1,303/max £2,198) | NHS Employers, NHS Terms and Conditions of Service Handbook, Pay Advisory Notice 02/2024, Annex 9, Table 1, https://www.nhsemployers.org/sites/default/files/pdf/21/18611.pdf | 2026-07-24 | Primary. |
| HCAS (England only) | 2026/27 (from 1 April 2026) | Inner 20% (min £5,794/max £8,746); Outer 15% (min £4,870/max £6,137); Fringe 5% (min £1,346/max £2,270) | Derived: 2025/26 primary figures above × 1.033 (the confirmed AfC 2026/27 uplift). Cross-checked against secondary aggregator figures, which matched exactly. | 2026-07-24 | 🚩 Derived, not read directly from an official 2026/27 HCAS table — the official Pay Advisory Notice 02/2026 Annex 9 could not be located/fetched (404/403). Verify against NHS Employers before relying on it. |
| NHS Pension Scheme 2015, employee tiered contribution rates | 2025/26, 2026/27, 2027/28 (identical across all three) | ≤£13,259: 5.2%; £13,260–£27,797: 6.5%; £27,798–£33,868: 8.3%; £33,869–£50,845: 9.8%; £50,846–£65,190: 10.7%; £65,191+: 12.5% | UK Statutory Instrument 2025 No. 821, https://www.legislation.gov.uk/uksi/2025/821/made | 2026-07-24 | Primary (the actual regulation). Supersedes conflicting figures seen on secondary "NHS pay calculator" sites, which quoted different, incorrect 2026/27 thresholds (e.g. £28,854 instead of £27,797) — those are wrong. Tiers select on **whole-time equivalent annualised pensionable pay** (see `docs/DATA_SOURCES.md` risk note + `src/calc/pension.ts`). |
| NHS Pension Scheme 2015, employer contribution rate | 2025/26 & 2026/27 | 23.7% of pensionable pay | Secondary source only — NHSBSA's own "NHS Pension Scheme employer contribution rates" pages returned 403 Forbidden to automated fetch during research; figure taken from search-result summaries of that page. | 2026-07-24 | 🚩 Verify directly at nhsbsa.nhs.uk/nhs-pension-scheme-employer-contribution-rates-202526 and -202627 before relying on it — this is informational/supplementary in the app (employer cost is shown, not deducted), so lower risk than the employee-facing figures above, but still unverified against the primary page. |
| Income tax, England & Northern Ireland (rUK) | 2025/26 & 2026/27 (unchanged) | Personal allowance £12,570; basic rate 20% to £50,270; higher rate 40% to £125,140; additional rate 45% above | HM Treasury / gov.uk "Income Tax rates and Personal Allowances"; corroborated by House of Commons Library "Direct taxes: Rates and allowances for 2026/27" | 2026-07-24 | Personal allowance has been frozen at £12,570 since 2021/22; frozen further via the 2025 Autumn Budget. Do not trust the £13,000 figure seen on some clone sites — it is wrong. |
| Income tax, Wales | 2025/26 & 2026/27 | Same as rUK (see above) | LITRG "Welsh income tax" overview; Welsh Rates of Income Tax operate as rUK rate ± 0% since devolution began, no divergence to date | 2026-07-24 | 🚩 Secondary confirmation only — the Welsh Rates of Income Tax ready reckoner PDF (gov.wales) could not be text-extracted. Verify against gov.wales before shipping. |
| Income tax, Scotland | 2025/26 | Starter 19% £12,571–£15,397; Basic 20% £15,398–£27,491; Intermediate 21% £27,492–£43,662; Higher 42% £43,663–£75,000; Advanced 45% £75,001–£125,140; Top 48% over £125,140 | gov.scot, "Scottish Income Tax 2026 to 2027: technical factsheet", https://www.gov.scot/publications/scottish-income-tax-technical-factsheet/ | 2026-07-24 | Primary. |
| Income tax, Scotland | 2026/27 | Starter 19% £12,571–£16,537; Basic 20% £16,538–£29,526; Intermediate 21% £29,527–£43,662; Higher 42% £43,663–£75,000; Advanced 45% £75,001–£125,140; Top 48% over £125,140 | Same as above | 2026-07-24 | Primary. |
| National Insurance (Class 1) | 2025/26 & 2026/27 (unchanged) | Employee: Primary Threshold £12,570/yr, 8% up to Upper Earnings Limit £50,270/yr, 2% above. Employer: Secondary Threshold £5,000/yr, 15% above, no upper limit. | gov.uk "National Insurance rates and categories"; corroborated by multiple accountancy-firm summaries of the Autumn Budget 2024 changes (13.8%→15%, £9,100→£5,000 secondary threshold from April 2025) | 2026-07-24 | Employer secondary threshold cut and rate rise both took effect 6 April 2025 and are unchanged for 2026/27. |
| Student loan plan thresholds | 2025/26 | Plan 1 £26,065; Plan 2 £28,470; Plan 4 £32,745; Plan 5 £25,000; Postgraduate £21,000. Rates: 9% (Plans 1/2/4/5), 6% (Postgraduate). | HMRC "2025 to 2026: Student and Postgraduate Loan deduction tables" (SL3), https://www.gov.uk/government/publications/sl3-student-loan-deduction-tables/2025-to-2026-student-and-postgraduate-loan-deduction-tables ; gov.uk "Student loans: a guide to terms and conditions 2025 to 2026" | 2026-07-24 | Primary. Plan 5 repayments only became due from April 2026 (courses starting Aug 2023+), so most 2025/26 payslips wouldn't yet show a Plan 5 deduction even though the threshold is defined. |
| Student loan plan thresholds | 2026/27 | Plan 1 £26,900; Plan 2 £29,385; Plan 4 £33,795; Plan 5 £25,000; Postgraduate £21,000. Rates: 9% (Plans 1/2/4/5), 6% (Postgraduate). | gov.uk "Student loans: a guide to terms and conditions 2026 to 2027", https://www.gov.uk/government/publications/student-loans-a-guide-to-terms-and-conditions/student-loans-a-guide-to-terms-and-conditions-2026-to-2027 | 2026-07-24 | Primary ("with effect from April 2026" table, read directly). |
| Salary sacrifice / NHS Pension interaction | — | Modelled as reducing pensionable pay (the England & Wales rule) | NHSBSA guidance and multiple NHS trust salary-sacrifice policy documents (secondary-source aggregation, not a single primary NHS Pensions page) | 2026-07-24 | 🚩 **Nation-specific nuance not fully modelled**: in Scotland, cycle-to-work and childcare salary sacrifice specifically do **not** reduce pensionable pay (protected), unlike England/Wales. This app applies the England/Wales rule uniformly to all nations and to all sacrifice types (not just cycle-to-work/childcare). Verify against NHS Pensions Scotland guidance before relying on Scottish salary-sacrifice figures. The WTE pay used for pension tier lookup is reduced by the actual (not FTE-grossed-up) sacrifice amount — a simplification for part-time staff, see `src/calc/index.ts`. |
| Automatic enrolment qualifying earnings thresholds (NEST) | 2025/26 & 2026/27 (unchanged) | Lower threshold £6,240/yr; upper threshold £50,270/yr; earnings trigger £10,000/yr | The Pensions Regulator, "Automatic enrolment earnings thresholds", https://www.thepensionsregulator.gov.uk/en/employers/new-employers/im-an-employer-who-has-to-provide-a-pension/declare-your-compliance/ongoing-duties-for-employers/earnings-thresholds | 2026-07-24 | Primary. 2026/27 explicitly confirmed maintained at 2025/26 levels (DWP written statement, Dec 2025). |
| NEST minimum contribution rates & relief-at-source mechanics | — | Statutory minimum 8% of qualifying earnings: 3% employer + 5% employee "gross equivalent" (4% actual payslip deduction + 1% government basic-rate tax relief top-up added directly to the pot) | gov.uk / DWP automatic enrolment guidance; corroborated by NEST's own "How is tax relief calculated" page, https://www.nestpensions.org.uk/schemeweb/helpcentre/contributions/calculating-contributions/calculate-tax-relief.html | 2026-07-24 | 🚩 The 4%/1% split assumes a basic-rate taxpayer on relief-at-source, NEST's default. Higher/additional-rate taxpayers on relief-at-source pensions can claim further relief via Self Assessment, which is **not modelled** here — this app only shows the automatic 1% top-up, not any extra relief a higher earner could separately claim. |

## Known risks / verification checklist before treating any output as authoritative

- 🚩 **Scotland inflation-guarantee top-up**: the 2025/26 and 2026/27 Scottish AfC pay
  deal includes a CPI-linked "inflation guarantee payment" that can increase the
  headline uplift (4.25%/3.75%) further, decided each January/March based on
  ONS data. This is **not modelled** — Scotland figures reflect only the base
  negotiated uplift, which is a floor, not necessarily the final paid amount.
- 🚩 **Northern Ireland pay scale is an approximation** (see table above) — treat
  with the least confidence of the four nations.
- 🚩 **HCAS floor/ceiling pro-rata order**: implemented as computing the HCAS
  amount at whole-time-equivalent level first, then pro-rating by hours — confirm
  against the AfC Terms and Conditions Handbook before relying on part-time HCAS
  figures.
- 🚩 **Pension tier lookup basis for part-timers**: implemented using whole-time
  equivalent annualised pay to select the tier %, then applying that % to actual
  pay — this is the single most common source of error in calculators like this
  for part-time staff. Cross-check against NHSBSA's "Cost of being in the Scheme"
  guidance (page returned 403 to automated fetch during research; a human should
  check it directly at nhsbsa.nhs.uk/member-hub/cost-being-scheme).
- 🚩 **Wales tax band mirroring rUK** and **NI pay scale = England's** are both
  secondary-sourced assumptions, not read from a primary Welsh/NI table directly.
- 🚩 **Salary sacrifice reduces pensionable pay everywhere** in this app (the
  England/Wales rule) — Scotland's cycle-to-work/childcare pension protection is
  **not modelled**, so Scottish users with those specific schemes will see their
  pension contribution (and hence take-home pay) understated relative to reality.
- 🚩 **Plan 5 student loan** repayments only became due from April 2026 — the
  2025/26 threshold (£25,000) is included for completeness but few real 2025/26
  payslips would have applied it yet.
- 🚩 **NEST higher-rate tax relief**: this app shows the automatic 1% basic-rate
  relief-at-source top-up only. A higher/additional-rate taxpayer on NEST is
  entitled to claim further relief via Self Assessment, which this calculator
  does not account for — their real net cost of pension saving is lower than
  shown.

Before enabling any `it.todo` worked-example test assertions in
`src/test/calc/worked-examples.test.ts`, manually recompute at least one England
and one Scotland example by hand against this table and/or HMRC's own online
calculator.