What this calculator does
Between £100,000 and £125,140 of adjusted net income, each extra pound of salary costs you 60p in income tax and 2p in National Insurance. That is the 60% tax trap, sometimes called the £100k tax trap. It is not a published rate. It comes from the Personal Allowance taper.
Enter your pay and any pension or Gift Aid payments. The calculator shows:
- your adjusted net income and how much Personal Allowance you have left;
- income tax band by band, and employee Class 1 National Insurance;
- the rate you pay on your next £100 of salary;
- the pension contribution that brings adjusted net income back to exactly £100,000, by salary sacrifice and by a personal pension, with what each one costs you in take-home pay;
- a warning when you are over the £100,000 limit for Tax-Free Childcare and the working-parent free childcare hours.
It uses the 2026 to 2027 tax year (6 April 2026 to 5 April 2027) for England, Wales and Northern Ireland. Scotland sets its own income tax bands, so the figures here are wrong for Scottish taxpayers.
How the calculation works
1. Adjusted net income
HMRC starts from your taxable income, takes off pension contributions made gross (salary sacrifice never reaches your taxable pay, and a net pay workplace scheme is taken off before tax), then takes off the grossed-up value of relief at source pension contributions and Gift Aid. Grossed up means what you paid plus basic rate tax, so every £1 you pay counts as £1.25.
Adjusted net income = salary − salary sacrifice − net pay pension + other income − 1.25 × (personal pension paid + Gift Aid paid)2. The Personal Allowance taper
The standard Personal Allowance is £12,570. It goes down by £1 for every £2 of adjusted net income above £100,000, and is zero from £125,140.
Personal Allowance = max(0, 12,570 − (adjusted net income − 100,000) ÷ 2)3. Income tax
Taxable income is total income minus the allowance that is left. The first £37,700 of taxable income is taxed at 20%, income up to £125,140 at 40%, and anything above at 45%. A relief at source contribution or Gift Aid donation pushes both of those limits up by its grossed-up amount. That is how higher rate relief is given.
4. National Insurance
Employees in category A pay 8% on earnings between £12,570 and £50,270 a year and 2% above that. Salary sacrifice reduces the pay NI is charged on. A net pay pension, a personal pension and Gift Aid do not. The calculator treats pay as spread evenly over the year; NI is really worked out per pay period, so a large bonus in one month can shift the figure slightly.
Why the rate is 60%
Take £1 of extra salary inside the taper. It is taxed at 40%, which is 40p. It also removes 50p of Personal Allowance, so 50p that was tax-free is now taxed at 40%, which is another 20p. Total: 60p of income tax. Add 2p of NI and you keep 38p.
Worked example: a £110,000 salary
Asha earns £110,000 and has no pension or Gift Aid payments outside work.
| Step | Amount |
|---|---|
| Adjusted net income | £110,000 |
| Over £100,000 by | £10,000 |
| Allowance lost (half of £10,000) | £5,000 |
| Personal Allowance left | £7,570 |
| Taxable income (£110,000 − £7,570) | £102,430 |
| £37,700 at 20% | £7,540 |
| £64,730 at 40% | £25,892 |
| Income tax | £33,432 |
| NI: £37,700 at 8% + £59,730 at 2% | £4,210.60 |
On £100,000 the same sums give £27,432 of tax and £4,010.60 of NI. So the last £10,000 cost her £6,000 in tax and £200 in NI. She keeps £3,800 of it.
Option A: salary sacrifice of £10,000
Her pay for tax and NI becomes £100,000. She saves £6,000 of tax and £200 of NI. Her take-home pay falls by £3,800, and £10,000 goes into her pension. Each £1 in the pension cost her 38p.
Option B: a personal pension (relief at source)
She pays £8,000. The provider claims £2,000 of basic rate relief, so £10,000 lands in the pension and her adjusted net income is £100,000. Her full £12,570 allowance returns, and her basic rate band grows to £47,700. Tax is £47,700 × 20% = £9,540 plus £49,730 × 40% = £19,892, a total of £29,432. That is £4,000 less than before, which she gets back through Self Assessment or her tax code. Net cost: £8,000 − £4,000 = £4,000 for £10,000 in the pension. No NI is saved, so this route costs £200 more than salary sacrifice.
The £100,000 childcare cliff
The taper is gradual. The childcare limit is not. If your or your partner's expected adjusted net income is over £100,000 for the tax year, you cannot use Tax-Free Childcare. In England you also lose the working-parent free hours (up to 30 hours a week for children from 9 months, for 38 weeks a year). Tax-Free Childcare is worth up to £2,000 a year per child, or £4,000 for a disabled child. One pound over the line loses all of it, which is why a pension contribution that lands you at or just under £100,000 can be worth far more than the tax saved.
Wales and Northern Ireland run their own funded childcare schemes with their own rules. Tax-Free Childcare applies across the UK.
What this calculator leaves out
- Scottish income tax bands.
- Savings interest and dividends, which have their own allowances and rates. Leave them out of "other income".
- Student loan and postgraduate loan repayments.
- The High Income Child Benefit Charge.
- Self-employed Class 2 and Class 4 National Insurance.
- Pension annual allowance limits and the tapered annual allowance. Large contributions can trigger a charge.
- Employer NI savings that some employers pass on when you sacrifice salary.
The allowance, the basic rate limit and the NI thresholds are frozen at their current levels until 5 April 2031, under a measure announced at Budget 2025. Pay rises during the freeze pull more people into the taper each year.