UK Marginal Tax Rate Cliffs 2026/27 — The Full Curve

Every UK income level's effective marginal tax rate, 2026/27 — engine-computed cliffs: PA taper, HICBC and rate thresholds, ranked worst-first.

The full curve, £0–£250,000 (2026-27)

Effective marginal rate (income tax + employee NI) at every £1,000 of gross income, England/Wales/Northern Ireland. The dashed line adds a Student Loan Plan 2 repayment (9.0% above £29,385) as an overlay scenario.

Computed from calculateUKIncomeTax and calculateNationalInsurance (this site's own engine) as a forward difference over each £100 of income, sampled every £1,000 plus exact threshold edges. Marriage Allowance and Blind Person's Allowance excluded.

The cliffs, ranked

Why the £50,270 jump isn't as bad as it looks

Income tax alone jumps from 20.0% to 40.0% at the Higher-rate threshold — a 20.0% step that looks dramatic in isolation. But the Upper Earnings Limit for employee National Insurance is deliberately set at the same £50,270 figure, so NI drops from 8.0% to 2.0% at exactly the same point. The two changes partly cancel: the real combined jump is 14.0% (28.0% → 42.0%), not 20.0%. It is still the first real cliff on the curve — just a smaller one than the headline income-tax rate suggests.

The £100k Personal Allowance taper

Between £100,000 and £125,140 of adjusted net income, the £12,570 Personal Allowance is withdrawn £1 for every £2 earned. Each extra £1 exposes 50p of previously tax-free income to the 40.0% Higher rate — a 20.0% tax-on-tax effect on top of the 40.0% Higher rate and 2.0% NI already due, for a flat 62.0% across the whole zone. A Plan 2 student loan borrower in the same zone faces 71.0% — the steepest sustained rate anywhere on this curve. For the full salary-by-salary breakdown, the Scottish comparison, and the pension-contribution exit strategy, see our companion 100k Tax Trap by Salary research.

The High Income Child Benefit Charge zone

Between £60,000 and £80,000 of individual adjusted net income, Child Benefit is clawed back 1 percentage point per £200 of income above the lower threshold — a true step function, not a smooth rate. Averaged across the zone, that adds roughly the following on top of the baseline 42.0% Higher-rate income tax + NI:

HICBC applies to the higher earner's individual income, not combined household income, and sits entirely below the £100,000 PA taper zone — the two never overlap for a single earner. Full mechanics and opt-out steps: our Child Benefit Calculator.

The £100,000 childcare hard cliff

This one isn't a marginal rate at all — it's a step. The instant either parent's adjusted net income passes £100,000, the household loses eligibility for Tax-Free Childcare (worth up to £2,000/child/year) and 30 hours free childcare in England (1,140 hours/year for children aged 9 months to 4). Government sets no single official £ value for the free hours — it depends on local provider rates — so we estimate roughly £8,600/child/year using the Coram Family and Childcare Survey 2026's average part-time market rate. For 2 pre-school children, that's a combined loss of roughly £21,200/year at exactly £100,001 — before any income tax is even considered.

Scotland is different

This study models rest-of-UK (England, Wales, Northern Ireland) income tax bands throughout. The Personal Allowance taper itself is reserved and applies UK-wide, but Scotland's own bands sit differently around it — the £100,000–£125,140 taper zone falls inside Scotland's 45.0% Advanced rate rather than England's 40.0% Higher rate, producing a steeper combined figure than the 62.0% shown above. See our England vs Scotland Tax Comparison and UK Tax Brackets & Bands Reference for the Scottish figures, or our companion 100k Tax Trap by Salary research for the Scottish taper calculation worked through in full.

Methodology

Every rate on this page is computed at build time from UK Tax Tools' own calculateUKIncomeTax and calculateNationalInsurance functions (the same engine behind the Income Tax and Take-Home Pay calculators) for the 2026-27 tax year, England/Wales/Northern Ireland bands, employed status, no Marriage Allowance or Blind Person's Allowance. The effective marginal rate at income X is the forward difference (tax due at X+£100 minus tax due at X) ÷ £100. The Student Loan Plan 2 overlay adds 9.0% above £29,385 via calculateStudentLoan. HICBC figures use calculateChildBenefit and report the smoothed average rate across each zone rather than the raw £200-stepped staircase. The Tax-Free Childcare and 30-hours figures are documented HMRC/gov.uk eligibility values, not tax-engine output — the 30-hours £ estimate is sourced separately and flagged as an estimate above.

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