Hundred SummersThe £100k childcare cliff: priced, with the way back under
Between £100,000 and £125,140 every pound bears ~60% tax as the personal allowance tapers away. For parents of young children it's far worse: at £100,001 of adjusted net income the free childcare hours and Tax-Free Childcare vanish entirely; a cliff, not a taper, often worth £10,000–£15,000 a year. This calculator prices both on the Hundred Summers app's own tax bands, and shows the pension contribution that restores everything. Your figures never leave your browser.
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Worked example
Computed when this page was built by the same engine that runs the calculator above, so the figures below and the live tool can never disagree. Change any input above to see your own.
| Inputs | |
|---|---|
| Adjusted net income | £110,000 |
| Childcare support at stake a year | £11,000 |
| Results | |
|---|---|
| Income over £100,000 | £10,000 |
| Extra tax in the 60% zone | £6,000 |
| Childcare support lost | £11,000 |
| Total cost of crossing the line | £17,000 |
| Pension contribution to get back under | £10,000 |
| Its net cost after tax saved and support regained | £-7,000 |
The next question
What does the rest of the £100,000 to £125,140 band cost? →60% tax trap calculator
Or answer it with everything else: the full Hundred Summers plan connects your pay, pensions, savings, property, tax and spending year by year, and stress-tests them across 500 simulated market histories.
Read the guides
- The 60% tax trap: earning between £100,000 and £125,140 →Why every pound between £100,000 and £125,140 is effectively taxed at 60% (62% with NI), how the personal allowance taper creates it, and why pension contributions in this zone get the best relief in the UK tax system.
- The £100k childcare cliff: the worst-designed threshold in UK finance →Cross £100,000 of adjusted net income by £1 and you lose all free childcare hours and Tax-Free Childcare: on top of the 60% tax zone. How the cliff works, which parent counts, and the pension escape route.
Why this is the worst-designed cliff in UK finance
Cliffs punish the pound, not the income. A parent on £99,999 with two nursery-age children keeps support worth perhaps £15,000; at £100,001 it is all gone: an effective marginal rate on those two pounds measured in the hundreds of thousands of percent. The test is each parent's adjusted net income separately: a household on £99k + £99k keeps everything, a single earner on £101k loses it all. No taper, no phase-out, no appeal.
The escape is mechanical: adjusted net income is income minus gross pension contributions (and Gift Aid), so contributions duck back under the line and reclaim tax and support at once. Bonus years are the danger, a one-off bonus can cost more in lost support than it pays, and salary sacrifice adds NI savings on top of what this page shows. The full Hundred Summers plan models the 60% zone in every projected year, and the cliff guide covers the edge cases: which parent counts, when eligibility is reconfirmed, and the bonus-sacrifice playbook.