SumAtlas is an independent UK reference site. Our mission is simple: take the rules that govern your money — Income Tax, National Insurance, Stamp Duty, Universal Credit, student loans, pensions and dozens more — and translate them into calculators and explanations that make sense the first time you read them.
Government guidance is often technically correct but practically useless. It is written for civil servants and accountants, not for the person trying to work out whether a pay rise is worth it, how much Stamp Duty they owe, or what they can actually claim. We exist to close that gap.
Until October 2026 we were called GovMath, at govmath.co.uk. We changed our name as we grow beyond the UK: the UK calculators now live at sumatlas.com/uk, and old govmath.co.uk links take you straight to the same page here.
What we do
Every SumAtlas tool follows the same promise. You get a fast, accurate calculator at the top of the page, and underneath it a plain-English explainer that covers three things:
- How we calculated your result — the maths, step by step, with no hidden assumptions.
- The official UK rules in simple English — what the law or HMRC/DWP guidance actually says.
- Common pitfalls — the traps and edge cases that catch people out, so you can avoid them.
Our principles
- Free, forever. No paywalls, no sign-ups, no email harvesting. We keep the lights on with unobtrusive advertising.
- Privacy-first. Calculations run in your browser. We do not store the figures you type in. See our Privacy Policy.
- Plain English. If a sentence needs a glossary, we rewrite the sentence.
- Kept current. Our figures track the latest published rates — currently the 2026/27 tax year.
How we keep figures accurate
Our rates and thresholds come from primary sources: GOV.UK, HM Revenue & Customs (HMRC), the Department for Work and Pensions (DWP), the Driver and Vehicle Licensing Agency (DVLA) and the devolved administrations in Scotland and Wales. When the government updates a rate, we update the calculator and note the tax year it applies to.
That said, SumAtlas provides estimates for general information. We are not a substitute for professional advice — read our Disclaimer for the full picture.
Our editorial standards
- Official sources first. Every rate, threshold and rule comes from a primary source, such as GOV.UK, HMRC, the DWP, Student Finance England, the Valuation Office Agency or the Scottish, Welsh and Northern Ireland governments. Each guide lists its sources at the end.
- One set of sums. The figures in our guides and worked examples are produced by the same calculation code as the calculators, not typed in by hand, so the guide and the calculator always agree.
- Tested. The calculation code is checked by hundreds of automated tests against official examples and published tables before any change goes live.
- Checked and dated. Each calculator shows when its page last changed. We recheck figures each April when the new tax year starts, and whenever the government announces a change.
- Clear about limits. Each calculator says what it assumes under "What we assumed", so you can see whether the answer fits your situation.
Read the full details in how we check our figures.
Who runs SumAtlas
SumAtlas is an independent UK website, written and maintained by the SumAtlas team. Every calculator and guide is checked by the team against the official sources it lists before it is published.
We are not affiliated with HMRC, the DWP, or any part of HM Government, and no bank, lender or financial firm pays to appear on the site. SumAtlas is free to use and funded by advertising, which never affects our figures.
Get in touch
Spotted an error, or want a calculator we haven't built yet? We genuinely want to hear it — head to our contact page. Corrections are prioritised.