Our calculation methodology

We prioritise official sources

Where a calculator depends on UK tax, government rules or statutory thresholds, we aim to base the calculation on information published by official UK government sources.

We explain important assumptions

Calculators cannot represent every individual circumstance. Where assumptions are necessary, we aim to make important limitations visible on the relevant calculator page.

For example, our current Salary Calculator supports Income Tax calculations for England, Wales and Northern Ireland. Scottish Income Tax is not currently calculated.

Salary Calculator methodology

The Salary Calculator starts with the annual gross salary entered by the user and estimates applicable deductions before calculating annual take-home pay.

2026/27 Salary Calculator assumptions

How we check calculations

Before a rate-dependent calculator is treated as ready for launch, it should be tested using different values, including values around important thresholds and edge cases.

When tax rates, thresholds or rules change, affected calculators should be reviewed and their visible review date updated after the calculation has been checked.

Estimates, not financial advice

My UK Tools provides general informational calculations. Results are estimates and should not be treated as financial, tax, legal or professional advice.

Your actual results may differ because of individual circumstances, payroll methods, tax codes, benefits, deductions or other factors not included in a calculator.