How SalaryTax UK is researched, verified, and maintained

SalaryTax UK is published as an institution, not under individual bylines. This page documents the accountability stack behind every figure on the site - where the underlying numbers come from, how they are checked against primary sources, when they are refreshed, how corrections are logged, and what the site explicitly does not do. UK tax is set by Acts of Parliament, statutory instruments, and HMRC guidance; the trustworthy thing to publish alongside it is the audit trail back to those sources, not a face.

Editorial standards

Every income tax band, National Insurance threshold, statutory pay rate, and economic figure on SalaryTax traces to a primary-source publication. That means HMRC and gov.uk for UK-wide tax, gov.scot for Scottish income tax, gov.wales for the Welsh Rate of Income Tax, the Office for National Statistics for CPI inflation and Annual Survey of Hours and Earnings (ASHE) salary distributions, Companies House for filing fees, and sector-specific institutional publishers (NHS Employers for Agenda for Change and resident doctors' pay, the STPCD for teacher pay scales) for occupational benchmarks. We do not paraphrase secondary commentary as if it were primary, and figures are not taken from a language model's output. The rule is that a figure needs a citable primary source; where an audit finds one that does not have it, the figure is corrected or removed.

The calculation engine

Every calculator is a pure TypeScript function with no network or storage I/O. The Income Tax, National Insurance, student loan and other rates that change each April come from a per-tax-year ruleset, one file per supported year, each citing the gov.uk source it was checked against. Each calculator has unit tests, and the salary (including tax codes), National Insurance, dividend, student loan and Statutory Sick Pay calculators are also tested against HMRC's own published worked examples, with the source URL and retrieval date recorded in the test. The tests run before every commit and again in continuous integration on every push. The methodology page documents the same in more detail.

Data provenance index

Every dataset surfaced anywhere on the site has a public provenance entry at /data-sources with the authoritative source URL, the date we retrieved it, and the cadence on which we refresh it, so a reader, journalist, or auditor can trace a figure back to the gov.uk, gov.scot, gov.wales, or ONS publication that produced it.

Update cadence

Annual maintenance follows a fixed calendar so freshness is predictable rather than ad hoc:

• January - ONS CPI annual averages, ASHE median salary, and ASHE percentile data are refreshed from the most recent ONS releases.
• March - the next tax-year ruleset is built and tested ahead of the 6 April changeover, including bands, thresholds, NI rates, statutory pay caps, and dividend allowance.
• Budget - rate changes announced at a Budget are worked in once the HMRC policy papers and legislation are published, and cited to them.
• Continuous - a weekly automated link-check workflow scans every outbound gov.uk and ONS URL on the site and opens an issue when one breaks, so cited sources stay reachable.

Verification methodology

Where HMRC publishes a worked example - for instance of Income Tax, National Insurance, dividend tax, student loan or Statutory Sick Pay - it becomes a test fixture, and the test fails if our engine ever drifts from the HMRC figure. Calculators for which HMRC publishes no worked example are tested against figures worked by hand from the published rates. Tests record the source URL and retrieval date. Pre-rendered per-amount pages (e.g. take-home for £35,000 in Scotland) call the same functions, so they share that coverage. Separate checks scan the built site for rates that have been superseded and for statute or HMRC manual citations that do not resolve.

Correction policy

We maintain a public corrections log at /corrections. Any reader who finds a number that diverges from a published HMRC figure can email the address below with the calculator URL, the inputs they used, the figure we returned, and the figure they believe is correct (with the source). Confirmed reader reports are logged at /corrections. Every change, including those that come out of our own audits, is a dated commit, and figures are traced to a primary source wherever one exists.

Independence and funding

SalaryTax UK is operated independently. Tax-calculator and tax-data pages do not carry affiliate links - no broker, bank, accountancy practice, pension provider, or umbrella company pays us to influence what the calculators return or how a tax rule is explained. We do not take paid placements that affect methodology. Where the site is funded by display advertising in the future, the advertising network is disclosed and is not permitted to alter content. If a relationship is ever added that could be perceived as a conflict, it will be disclosed on the page where it applies and on the editorial policy.

Technical infrastructure

Every change ships through version control, so the history of every tax figure, guide paragraph, and calculator function is kept as a dated commit. Type checks, linting and the unit tests run before each commit; continuous integration then runs them again on every push together with a production build, a Playwright end-to-end suite across four device profiles, an orphan-page audit and checks for superseded figures. Weekly jobs check every outbound source link and take a PageSpeed Insights snapshot.

Compliance and licensing

Site content (methodology narrative, calculator interfaces, guide prose, derived statistics presentation) is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). Underlying tax rules and economic statistics remain under the public-sector licences set by their publishers - predominantly the Open Government Licence v3.0 from HMRC, ONS, gov.scot, and gov.wales. When reusing SalaryTax content, attribute "SalaryTax (salarytax.uk)".

Limitations - what SalaryTax is not

SalaryTax UK is an information tool. It is not a regulated financial-advice service. We are not authorised by the Financial Conduct Authority. The calculators do not provide personal recommendations on tax structuring, pension planning, investment selection, inheritance planning, or any activity that requires FCA authorisation. For personal financial advice that takes individual circumstances into account, use a firm authorised by the Financial Conduct Authority - you can check a firm on the FCA Financial Services Register. For complex tax situations (residency, non-dom, share schemes, complex partnership structures, IHT and trust planning), a Chartered Tax Adviser (CIOT) or a chartered accountant (ICAEW, ACCA, or ICAS) is the appropriate professional to consult.

Contact

For corrections, factual queries, or methodology questions, contact [email protected]. Privacy and consent practice is documented on the privacy page; a deeper institutional account of editorial process is at editorial policy; the per-figure provenance audit is at data sources; the full corrections register is at corrections; the calculation methodology is at methodology; and a general project overview is at about.