Your salary isn't the number that matters — your adjusted net income is. Add your pension sacrifice, an EV car scheme and your bonus, and see exactly where you land against the £100,000 personal-allowance taper and childcare cliff.
Illustration, not advice. Figures use standard 2026/27 assumptions and a simplified employment-income model — your payslip and scheme rules may differ.
For a lot of people the payslip is a menu now, not a single figure. Once you're choosing pension sacrifice, a car scheme, share plans and the rest, the number the tax system actually keys off is your adjusted net income — roughly your taxable income for the year, after things like personal pension contributions and Gift Aid come off.
Salary-sacrifice items (pension, EV car, SIP partnership shares) come off your gross pay before tax, so they lower that number. Taxable perks — private medical cover, a company car — get added to it. Not everything pulls the same way, which is exactly why it helps to see it in one place.
| What it is | Effect | How it works |
|---|---|---|
| Pension by salary sacrifice | ↓ Lowers it | £1 for £1. The pay is given up, so it never becomes salary — and you save National Insurance on it too. |
| Workplace pension on a net pay arrangement | ↓ Lowers it | £1 for £1. It comes out of your pay before tax, so it is already gone from taxable income. |
| Personal pension or SIPP (relief at source) | ↓ Lowers it | £1.25 for every £1 you pay in. Your provider reclaims basic-rate relief, and the grossed-up figure is what comes off. |
| Gift Aid donation | ↓ Lowers it | £1.25 for every £1 given. Grossed up the same way as a SIPP contribution. |
| Cycle to work, and other sacrifice schemes | ↓ Lowers it | £1 for £1, for the same reason as pension sacrifice — the pay never arrives. |
| Electric car by salary sacrifice | ↓↑ Both | Down by what you sacrifice, then up again by the car's taxable benefit — 4% of the list price in 2026/27, rising each year. |
| Bonus or overtime | ↑ Raises it | Counts as taxable income in the year it is paid, which is what pushes people over a line they cleared last year. |
| Taxable perks — private medical, a company car | ↑ Raises it | Added to your income as a benefit in kind. |
| Trade union or police federation relief | ↑ Raises it | The one thing HMRC adds back. For most people it is nothing. |
The calculator above takes all of these: the salary-sacrifice routes, a personal pension or SIPP, Gift Aid, a bonus and unpaid leave. The two own-pocket routes are grossed up for you.
Adjusted net income decides three thresholds, and £60,000 is the first of them. Above it the High Income Child Benefit Charge claws back 1% of your Child Benefit for every £200 of income over the line, so it is gone entirely at £80,000. It is assessed on the higher earner's adjusted net income — not household income, and not salary — which is why the figure this calculator works out is the one that matters. A pension contribution or salary sacrifice reduces it pound for pound.
At £100,000 of adjusted net income your tax-free personal allowance is withdrawn by £1 for every £2 over the line, gone entirely by £125,140 — an effective rate of about 60% across that band. And if you've young children, Tax-Free Childcare and the free-hours entitlement stop completely the moment you go a pound over. Both are cliff edges, not gentle slopes — so where you land relative to £100,000 can be worth thousands.
Sacrificing into a pension is usually the cheapest way under the line — you keep the money, it's just locked away. But once you've used your annual allowance, some people take a few days' unpaid parental leave (a day-one right since April 2026, up to four weeks a year if you've children under 18) or use a holiday buy-back scheme to shave gross pay and land back under £100,000 before the tax year ends. It's real income given up — worth it mainly when it rescues something bigger, like the childcare cliff. Add unpaid days in the calculator above to see the effect.
The £100,000 thresholds are UK-wide. But income tax rates differ in Scotland, so the tax you save on a sacrifice — and your marginal rate — are worked out on the correct band set. Pick your region above and the figures follow it.
Want the full story? Read what adjusted net income is and the lines it decides, how the modern payslip fits together, or the dedicated salary sacrifice pension calculator.
Doing a tax return? This calculator covers one piece of it — the full UK Self Assessment guide has the deadlines, who has to file, payments on account, and the reliefs people miss.