The Six-Figure Cliff: When a Pay Rise Above £100,000 Costs More Than It Pays

Few tax thresholds are as quietly expensive as the point at which the UK personal allowance begins to disappear. For 2026/27, most taxpayers can receive £12,570 of income before income tax starts. But for every £2 of income above £100,000, £1 of that allowance is withdrawn. By £125,140, the allowance has gone entirely.

That mechanism is simple. Its effect is not. Within the band, an extra £1 of income is taxed at 40%, and it also causes 50p of allowance to be lost. That lost allowance would have been taxed at 40%, so the combined effect is 40% plus 20%: an effective marginal rate of 60%. For a slice of income that many households regard as comfortably high, the tax system treats each additional pound more harshly than the additional-rate band above it.

Why £100,000 matters more than it looks

The £100,000 threshold is not a cliff edge in the sense that all tax rises at once. It is a taper, and that makes it easy to miss. The allowance is reduced gradually, so the 60% rate applies to income between £100,000 and £125,140. Above that point, the marginal rate falls back to 45% for additional-rate taxpayers, plus any National Insurance contributions that apply.

The taper is based on adjusted net income, not simply salary. That means it can include bonus, overtime, self-employed profits, rental income, savings interest and some pension income. A household that thinks of itself as earning £95,000 can cross the threshold through a one-off bonus or a good year of business profits. The result is a tax charge that feels disproportionate because, in cash terms, it is.

The arithmetic of the 60% band

Consider an employee earning exactly £100,000 who receives a £10,000 bonus. At £100,000, the personal allowance is £12,570 and taxable income is £87,430. Income tax is £27,432. At £110,000, the allowance has fallen by £5,000 to £7,570, so taxable income is £102,430. Income tax rises to £33,432. The extra £10,000 of gross bonus therefore produces £6,000 of extra income tax, leaving £4,000 before any other deductions. That is 60p of tax for every extra £1.

The same logic applies across the whole band. Compare £100,000 with £125,140: gross income rises by £25,140, but income tax rises by £15,084. The effective rate on that slice is again 60%. For a self-employed sole trader with £100,000 of taxable profit, an additional £8,000 contract can produce £4,800 of extra income tax before National Insurance, leaving £3,200. A landlord whose rental profit pushes them into the band can face the same outcome.

This illustration isolates income tax. National Insurance, student loan repayments, pension contributions and other deductions can change the final cash result. But the direction is clear: the £100,000 to £125,140 band is one of the most expensive stretches of the UK income tax system for anyone trying to increase their earned income.

Who gets caught

The popular image of the 60% taxpayer is a City executive or a high-profile professional. In practice, the band catches a much broader group. A senior teacher with a promotion, an NHS manager with unsocial-hours payments, a chartered engineer with a annual bonus, a small business owner with a strong trading year or a couple with one higher earner and a rental property can all cross £100,000 without feeling wealthy.

That matters because the tax is not always obvious until a self-assessment return is filed or a payslip is compared with the previous year. A pay rise that looks generous in gross terms can deliver a surprisingly small increase in net income. For employers, the same issue affects bonus design and retention. For the self-employed, it affects how profits are recognised and when capital expenditure is made.

Planning levers that actually change the number

The practical response is not to refuse extra income. It is to understand that the relevant number is adjusted net income, and that legitimate planning can reduce it. The aim is to avoid paying 60% on income that could instead be directed somewhere more useful.

Pension contributions

A pension contribution can restore some or all of the personal allowance by reducing adjusted net income. For an employee, a workplace pension using a net pay arrangement reduces taxable pay directly. For a personal pension or a relief-at-source arrangement, higher-rate relief is claimed through self-assessment. Within the 60% band, the effective benefit can be unusually strong because the contribution not only attracts tax relief but also reduces the allowance taper.

There are limits. Annual allowance rules, the tapered annual allowance for high earners, the money purchase annual allowance and affordability all matter. A contribution should not be made simply to chase a tax outcome if the money is needed for near-term spending. But for anyone already saving for retirement, redirecting part of a bonus into a pension is often the cleanest way to soften the cliff.

Charitable giving

Gift Aid donations can also reduce adjusted net income for taper purposes. A donor who gives to charity through Gift Aid may be able to restore part of the personal allowance while supporting a cause they value. Payroll giving can be useful for employees, although the interaction with the taper should be checked. This is not a reason to give money away that would otherwise be spent on essentials, but for households with an existing charitable commitment, the tax interaction is worth reviewing.

Timing and profit recognition

Timing is rarely a complete solution, but it can spread income more efficiently. A bonus deferred into the next tax year may avoid pushing this year's income deeper into the 60% band, provided next year's position is known. For the self-employed, the timing of capital expenditure, pension contributions and profit recognition can affect the adjusted net income figure. These decisions should be made on commercial grounds first; tax should shape the timing, not drive the business.

Salary sacrifice is one route, but it is not the only one. The principle is broader: reduce adjusted net income where it is sensible to do so, rather than assuming a higher gross figure is always better.

The planning question

The 60% tax trap is not a reason to turn down a promotion or refuse a bonus. It is a reason to model the net outcome before the decision is made. For anyone whose income is approaching £100,000, the useful question is not simply how much more they will earn, but how much of the next pound they will keep, and whether a pension contribution, charitable donation or timing decision can improve the result without damaging their broader financial plan.