About UK Tax Utility

Last updated 12 June 2026

UK Tax Utility is a free set of UK tax calculators and guides built and maintained by Tom Whitfield, a software developer. The site has one editorial rule: every figure comes from HMRC's published rates on gov.uk, every page links its source, and every calculator shows its working — so you never have to take a number on trust.

Who's behind this?

I'm Tom — a developer, not an accountant, and the site doesn't pretend otherwise. I got fed up with tax calculators that hand you a single opaque number with no working, no source, and no date, and built the tools I wanted to exist instead. What a developer can credibly do is read HMRC's published rules carefully, encode them precisely, test the arithmetic, and show it — and that's the entire promise here. What I don't do is give advice: for decisions about your own affairs, talk to HMRC or a qualified accountant.

How the numbers are kept right

Sourced: every rate and threshold is taken from gov.uk and linked from the page that uses it.
Tested: the calculation engines have automated tests pinning the maths — band boundaries, the £100k allowance taper, NI limits — before any page ships.
Date-stamped: each page shows when it was last verified, and the tax year it reflects.
Updated each April: when rates change at the new tax year, the engines and pages are re-verified against gov.uk.
Corrected fast: spotted something wrong? Tell me — corrections are the top of the queue.

How the site makes money

The tools are free and always will be. The site may carry advertising and some links to services (like business bank accounts or tax-filing apps) are affiliate links that can pay us a commission. Two hard rules: commercial relationships never change a calculator's output, and they're never a condition of using anything here. See the privacy policy for details.

Privacy by architecture

The calculators run entirely in your browser. Your income and expenses are never sent to a server — there isn't one to send them to. That's not a policy promise; it's how the site is built.