Who maintains this
Pursely is built and maintained by Andrei Vlaic. The tax engine, the figures and the annual updates are all maintained directly — there's no third party between the rules and your result.
How the calculations are made
Pursely runs a single, integer-precise UK tax engine — it works in whole pence rather than rounded pounds, so the breakdown adds up exactly. For each calculation it applies, together:
- Income Tax — the Personal Allowance and the progressive bands (basic, higher and additional rate), including the withdrawal of the Personal Allowance above £100,000 (the "60% trap").
- Income Tax region — separate handling for Scotland and for England, Wales and Northern Ireland, because the bands and rates differ.
- National Insurance — Class 1 employee contributions using the current thresholds and rates.
- Pension — relief-at-source, net-pay and salary-sacrifice arrangements, which affect tax and NI differently.
- Student loans — the current repayment plans and thresholds (Plans 1, 2, 4, 5 and postgraduate).
- Company car / Benefit-in-Kind — the appropriate percentage applied to a vehicle's P11D value, including the low rate for electric cars.
Every figure you enter is processed on your device (or, on the website, inside your browser). Nothing is sent to a server, so the calculation is private by construction — we never see your salary, and there's nothing for us to store.
Where the rules come from
The engine is built on official UK government figures, not third-party estimates:
- HMRC / gov.uk — Income Tax rates and allowances
- gov.uk — National Insurance rates and thresholds
- gov.scot — Scottish Income Tax rates and bands
- gov.uk / Student Loans Company — student loan thresholds and rates
- HMRC — company car (Benefit-in-Kind) appropriate percentages
Which tax years are covered
Pursely currently supports the 2025/26 and 2026/27 tax years, and is updated each April when new rates take effect — which is also why Premium is a simple annual subscription rather than a one-off.
How figures are verified
The engine's outputs are checked against a fixed set of reference cases built from the HMRC, gov.scot and Student Loans Company figures above — standard salaries with and without a student loan, pension contributions, Scottish rates, and the £100,000 allowance taper — plus a real UK payslip reproduced to the penny. These cases run automatically on every update, and the same reference cases are run against the website calculator, so results don't drift between tax years or between the app and the site.
What Pursely can't see — and its limits
Pursely produces a highly accurate estimate. Your actual payslip can still differ for reasons no calculator can know in advance, including:
- mid-year tax code changes issued by HMRC;
- emergency or non-standard tax codes (for example after starting a new job);
- employer-specific benefit or deduction schemes;
- arrears, back-pay or one-off adjustments.
Pursely provides estimates for guidance only and is not financial, tax or investment advice. Pension and projection figures are illustrative.
Found a figure that doesn't match your payslip?
We want to know. Accuracy is the whole point, so if Pursely's number doesn't match your real payslip, get in touch with the details — it's the fastest way to make the engine better for everyone.
Last updated June 2026 · maintained by Andrei Vlaic.