Data provenance
Data sources
Every dataset that powers a SalaryTax calculator is documented here with its authoritative source, retrieval date, and the cadence at which we refresh it. Last full audit: 2026-04-17.
For testing approach, regional coverage, and known limitations see our methodology.
Tax rules
| Data | Source | Retrieved | Update cadence |
|---|---|---|---|
| UK Income Tax bands (2023-24 through 2026-27; frozen to 2027-28) | gov.uk - Income Tax rates | 2026-04-17 | Annual (6 April) |
| Scottish Income Tax 2023-24 | gov.scot - Scottish Income Tax 2023-2024 | 2026-04-17 | Annual |
| Scottish Income Tax 2024-25 | gov.scot - Scottish Income Tax 2024-2025 | 2026-04-17 | Annual |
| Scottish Income Tax 2025-26 | gov.scot - Scottish Budget 2025-26 | 2026-04-17 | Annual |
| Scottish Income Tax 2026-27 | gov.scot - Scottish Income Tax rates and bands 2026-27 | 2026-04-18 | Annual |
| National Insurance Class 1 / 2 / 4 | gov.uk - National Insurance rates and categories | 2025-04-17 | Annual |
| Self-employed National Insurance rates | gov.uk - Self-employed NI | 2025-04-17 | Annual |
| Student loan thresholds (Plan 1, 2, 4, 5, PG) | gov.uk - Repaying your student loan: what you pay | 2025-04-17 | Annual (April) |
| High Income Child Benefit Charge | gov.uk - Child Benefit tax charge | 2025-04-17 | Annual |
| Marriage Allowance | gov.uk - Marriage Allowance | 2025-04-17 | Ad hoc |
| Dividend tax rates and allowance | gov.uk - Tax on dividends | 2025-04-17 | Annual |
| Personal Savings Allowance | gov.uk - Apply tax-free interest on savings | 2025-04-17 | Annual |
| Blind Person's Allowance | gov.uk - Blind Person's Allowance | 2025-04-17 | Annual |
| Welsh Rate of Income Tax (WRIT) | gov.wales - Welsh Rates of Income Tax | 2025-04-17 | Annual |
Economic data (ONS)
| Data | Source | Retrieved | Update cadence |
|---|---|---|---|
| CPI annual averages (series D7BT) | ONS - CPI D7BT | 2025-04-17 | Annual (January release) |
| UK median full-time salary | ONS - Annual Survey of Hours and Earnings 2024 | 2025-04-17 | Annual (October) |
| UK annual salary percentiles | ONS ASHE 2024 Table 1.7a (weekly x 52) | 2025-04-17 | Annual |
| Regional median salaries (12 UK regions) | ONS ASHE 2024 Table 5.7a | 2025-04-17 | Annual |
Role and job-band mapping
| Data | Source | Retrieved | Update cadence |
|---|---|---|---|
| NHS Agenda for Change pay scales | NHS Employers - Pay scales 2024/25 | 2025-04-17 | Annual |
| Teacher pay scales (England) | gov.uk - Teachers' pay scales and allowances | 2025-04-17 | Annual |
| Civil Service pay benchmarks | gov.uk - Civil Service pay remit guidance | 2025-04-17 | Annual |
| ONS SOC 2020 pay bands (Table 14 ASHE) | ONS ASHE 2024 Table 14 | 2025-04-17 | Annual |
Update process
- April - immediately after new tax year starts:
update
src/data/tax/uk-YYYY-YY.tswith published HMRC, gov.scot, and gov.wales rates; bumpCURRENT_TAX_YEAR; refresh golden fixtures; update NHS and teacher pay scales. - January - after ONS annual averages: update CPI annual averages and median salary figures from the latest ASHE release.
- October - when ONS publishes headline ASHE numbers: update regional medians and annual percentiles.
License
Site content (methodology narrative, calculator UX, presentation of derived data) is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). Underlying tax rules and economic statistics are public-sector information published by gov.uk, gov.scot, gov.wales, NHS Employers, and ONS - those retain their original licenses (predominantly the Open Government Licence v3.0). When reusing SalaryTax content, please attribute "SalaryTax (salarytax.uk)".