About SalarySum
SalarySum is a free set of UK salary and tax calculators built and maintained by Uthman Choudhury. Every figure comes from published HMRC, gov.scot, Revenue Scotland, Welsh Revenue Authority and ONS sources, stored in one versioned data file per tax year and checked with automated tests. There is no signup, no paywall and no data collection; the site is funded by display ads.
Who runs the site?
SalarySum is written and maintained by Uthman Choudhury, founder and editor, salarysum. The site launched in 2026 to give UK workers a fast, honest answer to “what will I actually take home?” without an email form in the way. Corrections and questions are welcome at hello@salarysum.co.uk.
How are the calculations done?
- One data file per tax year. Every rate, threshold and allowance for 2026/27, 2025/26, 2024/25 lives in a single versioned JSON file. A Budget change is a one-file edit, and every page on the site reads the same file, so figures never contradict each other.
- Annual PAYE method. Income tax is worked out on annual taxable income using marginal bands, with the personal allowance tapered above £100,000. Employee National Insurance uses the annual thresholds. Student loans mirror HMRC’s per-month calculation, rounding each month down to the pound.
- Pensions. Net pay contributions reduce taxable pay; salary sacrifice reduces pay for tax and NI; relief at source contributions are shown net of 20% relief and extend the basic rate band.
- Tax codes. When a code is entered it overrides the standard allowance. K codes add to taxable pay with the 50% cap. BR and D codes apply a flat rate. Emergency markers are explained but, because the site works annually, are treated as cumulative.
- Tests. The calculation engine has automated unit tests against published HMRC and gov.scot examples, including Scottish bands, the 60% taper, relief at source and all three property taxes. They run on every change.
- Client-side. Calculators run in your browser. The pre-calculated salary, hourly and tax code pages use the same code at build time, so they agree with the live tools.
Where does the data come from?
- HMRC: Rates and thresholds for employers 2026 to 2027
- GOV.UK: Income Tax rates and Personal Allowances
- gov.scot: Scottish Income Tax 2026 to 2027 rates and bands
- GOV.UK: Student loan repayment thresholds 2026 to 2027
- GOV.UK: Stamp Duty Land Tax rates
- Revenue Scotland: LBTT rates and bands
- Welsh Revenue Authority: LTT rates and bands
- ONS: Employee earnings in the UK 2025
Current data versions: 2026/27 (2026-27.1), 2025/26 (2025-26.1), 2024/25 (2024-25.1). Last reviewed . See the tax year changes page for what moved.
What the calculators do not cover
They are designed for employees paid through PAYE. They do not handle self-employment (Class 2 and 4 NI), dividends, savings interest, capital gains, benefits in kind beyond a tax code adjustment, Child Benefit clawback, Welsh rate divergence (none currently), Northern Ireland-specific student loan rules beyond Plan 1, or non-resident stamp duty surcharges. Results are estimates for guidance and are not financial, tax or legal advice.
How is the site funded?
Through display advertising served by Google AdSense. Ads are only personalised if you consent; otherwise they are non-personalised. Analytics are cookie-less. Your calculator inputs are never sent to us. See the privacy policy.
Contact
Spotted an error or a rate that has changed? Email hello@salarysum.co.uk with the page URL and the source, and it will be corrected and the data version bumped.