The UK 60% tax trap is the effective 60% marginal income tax rate that applies to adjusted net income between £100,000 and £125,140, caused by the withdrawal of the £12,570 personal allowance at a rate of £1 for every £2 of income above £100,000. It is not a published rate — you will not find "60%" in any HMRC table — but in the 2026/27 tax year every pound a London banker, lawyer or tech executive earns inside that £25,140 band keeps just 40 pence, before National Insurance takes another 2 pence.
For American citizens and Green Card holders working in the UK, the trap has a second layer that UK-only guides ignore: the planning moves that fix the UK problem — pension contributions, salary sacrifice, Gift Aid — behave very differently on a US Form 1040. A fix that saves 60% in the UK can quietly create taxable income, an unusable deduction or a smaller foreign tax credit on the American side. This guide covers both layers.
How the UK 60% tax trap actually works
The mechanics sit in the personal allowance rules rather than the rate tables. Everyone starts 2026/27 with a personal allowance of £12,570 — income taxed at 0%. Once your adjusted net income passes £100,000, HMRC withdraws that allowance at £1 for every £2 of income above the threshold. By £125,140 the allowance is gone entirely, as set out on the official income tax rates page on GOV.UK.
Inside the band, each extra £2 of income does two things at once: it is itself taxed at the higher rate of 40%, and it converts £1 of previously tax-free allowance into income taxed at 40%. Two pounds earned, £1.20 of tax — a 60% effective marginal rate. Above £125,140 the allowance has fully disappeared, the additional rate of 45% takes over, and the marginal rate actually falls. The UK is one of the few countries where earning £130,000 puts you on a lower marginal rate than earning £110,000.
The maths: what the band costs in cash
Take a straightforward example for 2026/27. A US citizen employed in London earns a £95,000 salary and receives a £20,000 bonus, taking adjusted net income to £115,000. The £15,000 above £100,000 costs £6,000 of income tax at 40% and strips £7,500 from the personal allowance, exposing that £7,500 to tax at 40% — another £3,000. Total tax on the £15,000 slice: £9,000, exactly 60%.
Run the full band and the numbers are stark: the £25,140 between £100,000 and £125,140 carries £15,084 of income tax — £10,056 at the headline 40% plus £5,028 from the lost allowance. You can test your own numbers in our UK 60% tax trap calculator, which applies the taper, the 2026/27 bands and employee National Insurance in one pass.
Adjusted net income: the number that decides everything
The taper is not tested against salary. It is tested against adjusted net income — broadly, total taxable income from all sources less gross personal pension contributions and gross Gift Aid donations, as defined in HMRC's adjusted net income guidance on GOV.UK.
That definition is what makes the trap both dangerous and fixable. Dangerous, because income you might not think about — bank interest above the savings allowance, dividends from a US brokerage account, rental profit on a flat you kept in the States, vested RSUs — all counts towards the £100,000 test. Fixable, because pension contributions and Gift Aid are subtracted before the test is applied, which is the entire basis of the escape routes below.
- Counts towards adjusted net income: salary, bonus, vested RSUs, self-employment profit, rental income, interest, dividends (including US-source dividends), pension withdrawals, most benefits in kind.
- Deducted from adjusted net income: gross personal pension contributions, employer pension contributions made by salary sacrifice (never in your income to begin with), gross Gift Aid donations, trading losses.
- Irrelevant to the test: ISA interest (though for Americans an ISA is rarely the shelter it appears — see our PFIC coverage), capital gains, employer pension contributions.
Who falls into the trap — and why it is a London problem
Frozen thresholds have turned a niche issue into a mass one. The £100,000 taper threshold has not moved since it was introduced in 2010; if it had tracked inflation it would sit above £150,000 today. With City salaries, banker and law-firm bonuses, and US tech RSU packages, a very large share of American professionals in London now cross £100,000 without feeling remotely rich in a city where childcare and housing absorb so much of it.
The trap is also spiky rather than smooth. A base salary of £90,000 stays clear all year — until a March bonus or a quarterly RSU vest lands £30,000 of income in a single tax year and drags £15,000 of it into the 60% band. Equity-compensated employees are hit hardest, because vesting schedules bunch income; our guide to US–UK taxation of RSUs and stock options explains how the two systems time that income differently.
The cliff on top of the trap: childcare at £100,000
For parents, £100,000 is not a taper but a cliff. Adjusted net income of even £1 over £100,000 ends eligibility for Tax-Free Childcare — worth up to £2,000 per child per year — and for the funded childcare hours offered to working parents in England. A family with two children in London nurseries can lose well over £10,000 of support because one parent earned £100,001 instead of £99,999.
Around the cliff itself, the effective marginal rate on the first pound over £100,000 is, strictly, several thousand percent. If one parent is near the threshold and childcare support is in payment, a pension contribution that restores adjusted net income to £100,000 or below is usually the single highest-returning financial decision available to that household in the year.
Escape route one: personal pension contributions
A gross personal pension contribution reduces adjusted net income pound for pound. Earn £120,000, contribute £16,000 gross (£12,800 net of basic-rate relief at source), and your adjusted net income is £104,000; contribute £20,000 gross and you are back at £100,000 with the full personal allowance restored. Relief inside the band is worth an effective 60% — you bank £60 of tax saving for every £100 that goes into the pension, before investment growth.
The annual allowance for 2026/27 is £60,000 (tapered for very high earners once threshold income passes £200,000 and adjusted income passes £260,000), and unused allowance from the previous three tax years can be carried forward. For most people in the £100,000–£125,140 band the allowance is not the constraint; cash flow is.
The American complication with pensions
Here is where US citizens must slow down. Contributions to a UK employer scheme are generally protected by Article 18(5) of the US–UK tax treaty: employee contributions can be excluded from US taxable income, and employer contributions are not taxed as they accrue. A contribution through your employer's scheme therefore usually works on both sides of the Atlantic.
A large personal contribution to a SIPP outside any employer arrangement is messier. The US gives no deduction for it — a SIPP is not an IRA — so the money is contributed out of income the US has already taxed, and aggressive relief-at-source top-ups can create timing mismatches between UK relief and US recognition. Worse, every pound of UK tax you save is a pound of foreign tax credit you no longer generate on Form 1116. If you are a high earner whose US liability is normally covered entirely by UK tax paid, shrinking the UK bill can surface a live US bill. The trap-fix still usually wins — 60% relief is hard to beat — but the net saving for an American is not the headline 60%, and the right contribution figure is a two-country calculation. Our guide to US taxation of UK pensions and SIPPs covers the treaty mechanics in depth.
Escape route two: salary sacrifice
Salary sacrifice — formally giving up salary in exchange for an employer pension contribution — is the cleanest version of the pension fix. The sacrificed amount never enters your income at all, so it never touches adjusted net income, and you save employee National Insurance at 2% on top of the 60% income tax effect. Many employers rebate part of their own 15% employer NI saving into the pension as well.
For US purposes, a sacrifice into an employer scheme sits squarely inside the Article 18(5) protection, which makes it the preferred route for most American employees. The practical constraints are employer-side: sacrifice usually has to be elected in advance, cannot take pay below the national minimum wage, and can interact with mortgage affordability testing because it reduces contractual salary. Model the numbers first with our UK salary sacrifice calculator.
Escape route three: Gift Aid — with a serious US caveat
Gift Aid donations reduce adjusted net income by the gross amount of the gift, so a £8,000 donation grossed up to £10,000 pulls £10,000 out of the taper calculation. Inside the band, charitable giving is effectively subsidised at 60% — generous by any international standard.
The US caveat: a donation to a UK charity is generally not deductible on a US return, because the US only allows deductions for gifts to US-qualified organisations (and most Americans abroad take the standard deduction anyway). Americans who give seriously should consider dual-qualified structures — vehicles recognised by both HMRC and the IRS — so a single gift earns relief in both systems. Donating US-side only, in contrast, does nothing for your UK taper. Sequencing matters, and this is a place where advice pays for itself; contact us before making a large one-off gift.
Timing income around the band: bonuses, RSUs and dividends
Because the trap is an annual test, income timing is a legitimate lever. Deferring a bonus into a year where you will be below £100,000 — or above £125,140 — moves that slice from 60% to 40% or 45%. RSU vesting is usually fixed by the plan, but sales, dividend timing on a personal portfolio, and the choice of tax year for exercising options are not. Married couples should also check whose name investment income sits in: moving income-producing assets to a lower-earning spouse takes that income out of the £100,000 test entirely.
One warning for Americans: the UK tax year ends on 5 April and the US tax year on 31 December, so a deferral that works beautifully for the UK taper can concentrate income into a single US calendar year and push you into the 37% federal bracket, the 3.8% net investment income tax, or additional Medicare tax. Every timing decision needs to be run through both calendars.
Scotland: the same trap, higher stakes
The personal allowance and its taper are UK-wide, but Scottish income tax rates on earnings are higher in the affected band. A Scottish taxpayer in the taper zone faces an effective marginal rate of around 67.5% on earned income where the 45% advanced rate overlaps the withdrawal band — meaningfully worse than the 60% in England, Wales and Northern Ireland. The escape routes work identically, and pension relief is correspondingly more valuable; if you are an American in Edinburgh or Aberdeen, the case for acting is simply stronger.
Self assessment mechanics: how the trap is collected
PAYE codes frequently get the taper wrong in-year, especially where bonuses or RSU income arrive unevenly, because your employer does not know your total adjusted net income. The reconciliation happens through self assessment: anyone with income over £150,000 must file, and HMRC expects those inside the taper band to file where tax is due. Underpayments surface as a January balancing payment, often with payments on account layered on top — a cash-flow shock for anyone who assumed PAYE had it covered.
Americans have the extra step of reporting the same income on a US return with a foreign tax credit computed on the UK tax actually paid. Getting the UK side right first, including the taper, is what makes the US side land cleanly. At TaxStone we prepare both returns together so the credits, the treaty positions and the taper interact the way they should.
What to do before 5 April 2027
The taper is an annual, all-or-nothing test — which means it rewards acting before the tax year closes, not after. Between now and 5 April 2027, anyone whose adjusted net income will land between £100,000 and £125,140 should estimate the year's income including bonuses and vests, decide the pension contribution or Gift Aid figure that either clears the band or accepts it deliberately, and elect any salary sacrifice changes in time for the payroll cut-off.
For US citizens, add one more step: model the same moves on the US side before executing, so a 60% UK saving is not partly clawed back by a foreign-tax-credit shortfall or an unexpected US liability. The right answer is almost always still to act — but the right amount is rarely the number a UK-only adviser would give you.
