£21,000 Salary — 20% Pay Rise After Tax
A 20% pay rise from £21,000 to £25,200 adds £4,200 to your gross pay. After income tax and National Insurance, you keep £3,024/year (£252/month) extra.
Before vs after — annual figures 2025-26
| Before (£21,000) | After (£25,200) | Change | |
|---|---|---|---|
| Gross salary | £21,000 | £25,200 | +£4,200 |
| Income Tax | −£1,686 | −£2,526 | −£840 |
| National Insurance | −£674 | −£1,010 | −£336 |
| Take-home/year | £18,640 | £21,664 | +£3,024 |
| Take-home/month | £1,553 | £1,805 | +£252 |
| Effective tax rate | 11.24% | 14.03% |
England 2025-26 rates. Personal Allowance £12,570. See Scotland for Scottish income tax.
Why you keep less than 20% of your pay rise
A 20% pay rise of £4,200 sounds significant, but the effective marginal tax rate on this additional income is 0.28% — meaning you only keep £3,024 of the £4,200 increase.
The marginal rate combines income tax (20% or 40% depending on your band) and employee NI (8% on earnings between £12,570 and £50,270, 2% above). A pay rise that pushes you into the higher rate band (above £50,270) will be taxed at 42% on the portion above that threshold.
Calculate your exact take-home pay
Other pay rises from £21,000
Understanding your pay rise after tax
When you receive a 20% pay rise from £21,000 to £25,200, the £4,200 increase in gross pay does not translate directly into more take-home pay. Income Tax and National Insurance are deducted from the additional earnings at your marginal rate — the rate that applies to the top slice of your income.
For most employees earning between £12,570 and £50,270, the marginal rate is 28%: 20% income tax plus 8% employee NI. Above £50,270, NI drops to 2% but income tax rises to 40%, giving a marginal rate of 42%. If your pay rise takes you over the £50,270 threshold, the portion above it is taxed at 42% rather than 28%.
If you want to maximise the benefit of your pay rise, consider salary sacrifice into a pension — contributions made this way reduce your taxable pay, effectively giving you the full gross value of part of your rise tax-free. You can also use a pension calculator to model the long-term impact.
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