← Calculators/Tax year 2026/27·Last reviewed
The £100k / 60% tax trap calculator
Set a target adjusted net income; the tool solves for the pension contribution that gets you there and shows, side by side, what you pay and lose now versus what you get back.
Free, no sign-up. Runs the same engine and the same versioned tax-year config the signed-in suite uses — nothing leaves your browser. How we verify the numbers.
The pension move
£18,000 into your pension for £7,200 out of pocket
60% effective relief. For every £1 it costs you, £2.50 lands in your pension — the taxman funds the rest.
Right now your next £1 of income is taxed at 62%.
Verify all inputs · Not financial or tax advice
For planning and illustration purposes only · Verify all inputs against source documents · This tool does not constitute financial or tax advice.
— In short
The “£100k tax trap” is the band of income between £100,000 and £125,140 where the personal allowance is withdrawn at £1 for every £2 earned — an effective marginal rate of 60% (67.5% in Scotland). Above £100,000 you also lose Tax-Free Childcare and the funded hours. A pension contribution that brings your adjusted net income back below £100,000 restores the allowance and the childcare, and the contribution still lands in your pension.
— How it's calculated
Adjusted net income — what counts
Adjusted net income is your total taxable income (salary, bonus, taxable benefits in kind, self-employment, property, dividends and savings) less grossed-up Gift Aid and grossed-up relief-at-source pension contributions. It is the figure that drives the personal-allowance taper, the High Income Child Benefit Charge and the £100,000 childcare cliff — and it is what a pension contribution reduces, £1 for every £1 of gross contribution.
ITA 2007 s.58 (adjusted net income) · s.35 (personal-allowance taper)
The contribution that gets you there
From your target adjusted net income the tool solves for the gross pension contribution required — then prices what it actually costs you net of relief. Relief-at-source and net-pay give the same tax relief; salary sacrifice gives the same tax relief and also saves employee National Insurance, so it costs less. The net cost is the gross contribution minus income-tax relief, any NI saving, any Child Benefit no longer clawed back and any childcare regained.
FA 2004 s.188–192 (pension tax relief) · SSCBA 1992 s.8 (employee NI)
Child benefit and the £100k childcare cliff
Between £60,000 and £80,000 the High Income Child Benefit Charge claws back 1% of your Child Benefit for every £200 of adjusted net income. Over £100,000 — for either parent — Tax-Free Childcare (up to £2,000 per child, £4,000 if disabled) and the working-parent funded hours are lost entirely. The funded-hours value shown is a labelled estimate based on the DfE national average funding rate; it varies by the child’s age, your local authority and provider.
ITEPA 2003 s.681B–681H (HICBC) · gov.uk/tax-free-childcare · DfE early-years funding rates
— Worked example
- Required gross pension contribution
- £18,000
- What it actually costs you (net)
- £7,200
- Personal allowance restored
- £3,570 → £12,570
- Income tax
- £38,232 → £27,432
- Effective relief on the contribution
- 60%
Computed live by the same engine the tool above runs. At a £100,000 target the personal allowance is fully restored; dropping below £80,000 would also stop the High Income Child Benefit Charge.
— Frequently asked questions
What is the £100k tax trap?
Between £100,000 and £125,140 of adjusted net income, the personal allowance is withdrawn at £1 for every £2 earned. That withdrawal, on top of the 40% higher rate, gives an effective marginal rate of 60% on that band (45% plus the withdrawal gives 67.5% in Scotland). You also lose Tax-Free Childcare and the funded hours over £100,000.
How much pension contribution do I need to avoid it?
A gross pension contribution reduces your adjusted net income £1 for £1, so the contribution needed is your adjusted net income minus your target. To get from £118,000 to £100,000, for example, you need an £18,000 gross contribution.
Is salary sacrifice cheaper than a personal pension?
It gives the same income-tax relief, and it also saves employee National Insurance on the sacrificed amount, so the net cost is lower. The tool shows both so you can compare.
Does the Scottish tax trap differ?
Yes. The personal-allowance withdrawal still applies, but on top of the Scottish advanced rate of 45% it produces an effective marginal rate of about 67.5% between £100,000 and £125,140 — switch the residence toggle to Scotland to see it.
What childcare do I lose over £100,000?
If either parent’s adjusted net income is over £100,000 you lose Tax-Free Childcare (up to £2,000 per child a year, £4,000 if disabled) and the working-parent funded hours, in full — there is no taper. A contribution that brings income back to £100,000 or below restores them.
— When you're ready
Need an exact annual-allowance headroom with taper and carry-forward? The pension workbench computes the full AA position across schemes.
With a free account, the same engine runs inside the workbench:
- save the calc to a client file, with the audit trail and sign-off workflow
- export the branded compliance annex PDF — full working, legislative references, config version
- multi-gain, multi-scheme and prior-year history the single-screen tools don't take
- upload statements and certificates — the figures are extracted for your review
Free plan: 3 calcs / month · no card required · cancel any time. Unlimited on Pro and Firm.
— Related
For planning and illustration purposes only · Verify all inputs against source documents · This tool does not constitute financial or tax advice.