What HMRC actually takes from £15,000 of side income depends on the salary it sits on top of. £1,000 is covered by the trading allowance; the remaining £14,000 is taxed at your marginal rate.
| Salary | Tax + NI | You keep | Effective rate |
|---|---|---|---|
| £15,000 | £2,886 | £12,114 | 19% |
| £20,000 | £2,886 | £12,114 | 19% |
| £25,000 | £2,886 | £12,114 | 19% |
| £30,000 | £2,886 | £12,114 | 19% |
| £35,000 | £2,886 | £12,114 | 19% |
| £40,000 | £3,632 | £11,368 | 24% |
| £45,000 | £4,632 | £10,368 | 31% |
| £50,000 | £5,632 | £9,368 | 38% |
| £60,000 | £5,686 | £9,314 | 38% |
| £80,000 | £5,686 | £9,314 | 38% |
| £100,000 | £8,486 | £6,514 | 57% |
Rules checked 18 August 2026 against GOV.UK pages showing the 2026/27 tax year. This is information, not tax advice; your Self Assessment is the authority on what you actually owe.