How we test our calculators
The worked examples we check our calculators against, with the results the official rules give. Last tested: 12 October 2026.
We test each calculator against examples worked out by hand from the official rules published on GOV.UK, by NHS Employers and by the NHS Business Services Authority. We take the 2026/27 rates and thresholds, work out the answer step by step, and check that the calculator gives exactly the same figure, to the penny.
The tables below show the examples. Every figure is for the 2026/27 tax year, with the standard tax code 1257L and no other income, unless the row says otherwise. You can open the calculator in each row and try the example yourself.
A worked example
Take a salary of £45,000 in England. The first £12,570 is your Personal Allowance, so £32,430 is taxed. All of that is in the 20% basic rate band, so Income Tax is £6,486. Employee National Insurance is 8% of pay between £12,570 and £50,270, which is 8% of £32,430, or £2,594.40.
Income Tax and National Insurance: England, Wales and Northern Ireland
| Scenario | What the official rules give | Calculator |
|---|---|---|
| Salary £20,000 | Income Tax £1,486; employee NI £594.40 | Income tax, National Insurance |
| Salary £45,000 | Income Tax £6,486; employee NI £2,594.40 | Income tax, National Insurance |
| Salary £60,000 | Income Tax £11,432; employee NI £3,210.60 | Income tax, National Insurance |
| Salary £110,000 | Personal Allowance reduced to £7,570; Income Tax £33,432; employee NI £4,210.60 | Income tax, National Insurance |
| Salary £150,000 | No Personal Allowance; Income Tax £53,703; employee NI £5,010.60 | Income tax, National Insurance |
Income Tax: Scotland
| Scenario | What the official rules give | Calculator |
|---|---|---|
| Salary £20,000 | Income Tax £1,446.33 | Income tax |
| Salary £45,000 | Income Tax £6,882.05 | Income tax |
| Salary £60,000 | Income Tax £13,182.05 | Income tax |
| Salary £110,000 | Income Tax £37,482.05 | Income tax |
| Salary £150,000 | Income Tax £59,634.35 | Income tax |
National Insurance is the same across the UK, so the NI figures in the first table apply in Scotland too.
Other calculators
| Scenario | What the official rules give | Calculator |
|---|---|---|
| Take home pay on a £35,000 salary in England, no pension or student loan | Income Tax £4,486; employee NI £1,794.40; take home £28,719.60 a year | Take home pay |
| Plan 2 student loan on a £35,000 salary | £505.35 a year | Student loan |
| Employer National Insurance on a £30,000 salary | £3,750 a year | Employer cost |
| Self-employed with £30,000 profit | Income Tax £3,486; Class 4 NI £1,045.80 | Self-employed tax |
| Marriage Allowance: couple earning £10,000 and £30,000 | Saving of £252 a year | Marriage Allowance |
| NHS Band 5 entry point (£32,073), full time, in the NHS Pension Scheme at 8.3% | Take home £24,482.51 a year | NHS Band 5 pay |
Why your payslip may differ
These figures are estimates for a whole tax year. Real payslips are worked out period by period, using your pay so far in the year, and rounded each time. So your payslip can differ from our figures by small amounts, or by more if your pay changed during the year or you have a different tax code.
If you find a difference you cannot explain, please tell us through the contact form. Tell us which calculator you used, what you entered and what you expected. We will check it against the official rules and fix it if we got it wrong.
Last tested: 12 October 2026.
Related pages
See how we calculate, every figure on the UK tax rates page, and our editorial policy.