The Personal Allowance taper over £100,000
The standard Personal Allowance is £12,570 in both 2025/26 and 2026/27, but it is not guaranteed at that level for every taxpayer. The official Income Tax rates and allowances page, updated on 6 April 2026, states that the income limit for the Personal Allowance is £100,000 in both years, that the allowance goes down by £1 for every £2 of income above that limit, and that it can go down to zero. This guide works through that rule, shows where the allowance disappears, and explains what our calculator does — and does not — include when it applies the taper.
The official arithmetic
For every £2 of income above £100,000, £1 of Personal Allowance is removed. At £100,000 the full £12,570 remains. At £100,002 it is £12,569, because only a complete £2 of excess has been reached. At £125,140 the excess is £25,140, half of that is £12,570, and the allowance is exactly zero. Above £125,140 there is no Personal Allowance left to remove, and additional-rate Income Tax can also apply, because the additional-rate band is officially described as income after allowances over £125,141.
The effect on the tax bill is larger than a simple 40% on the extra salary, because two things happen at once. Each extra £2 of income in the taper range loses £1 of tax-free allowance, so an extra £1 of income is brought into tax as well as the £2 you actually received. In the higher-rate band that extra £1 is taxed at 40%, which is why people describe a 60% marginal rate in this window: 40% on the £2, plus 40% on the £1 of allowance lost, is 80 pence of tax on £2 of income, or 40 pence in the pound plus another 20 pence in the pound. That 60% description is a way of talking about the marginal rate. It is not a separate official tax band, and it is not how HMRC labels the table. The legal mechanics remain “£1 off the allowance for every £2” plus the ordinary higher-rate (or, in Scotland, the relevant Scottish) band.
A worked example, using official 2025/26 rUK bands and labelled as an example, makes the jump visible. At £100,000 of employment income, the Personal Allowance is still £12,570, taxable income is £87,430, and Income Tax is 20% on £37,700 (£7,540) plus 40% on the remaining £49,730 (£19,892), which is £27,432. At £125,140 the allowance is zero, taxable income is £125,140, and Income Tax is £7,540 plus 40% on £87,440 (£34,976), which is £42,516. Those two official-rate calculations are built into our tax calculator and are covered by its tests.
What counts as “income” for the taper
The official rates page refers to income above the £100,000 limit. In a full Self Assessment computation, the taper is applied by reference to adjusted net income, which can be reduced by things such as certain pension contributions and Gift Aid. Our calculator does not model those reliefs. It adds together the employment, self-employment, property, pension, dividend and savings amounts you enter and uses that total as a simple stand-in. If you make reliefs that officially reduce adjusted net income, the taper in real life can be milder than the estimate; if you have income the boxes do not capture, it can be harsher. That limitation is stated on the tool page.
Dividends and savings count towards the total used for the taper even though they are taxed at their own rates after the allowance has been applied. A year with a modest salary and a large dividend can still lose some or all of the Personal Allowance. Scottish taxpayers use the same £100,000 official limit for the allowance; the taper is not a Scottish-only or rUK-only rule. What differs is the rate applied to non-savings, non-dividend income once the remaining allowance has been used.
How this meets the additional rate, and other charges
Once the allowance has fallen to zero, further income is taxed without that tax-free slice, and at £125,141 of income after allowances the additional rate of 45% (or the Scottish top rate of 48% on NSND income) officially begins. The Personal Allowance taper and the additional-rate threshold therefore meet at the same neighbourhood of income, which is why a small change around £125,140 is worth checking carefully on a return rather than rounding in your head.
The High Income Child Benefit Charge is a separate official rule, with its own £60,000 threshold from 2024/25, and is not the same as the Personal Allowance taper. You can be in one, both, or neither. Our main tax calculator does not model the Child Benefit charge; see the High Income Child Benefit Charge guide for the official thresholds. Marriage Allowance and Blind Person’s Allowance are also outside the main calculator. If those apply, HMRC’s computation on the return, or a qualified adviser, is the place to put them.
Planning notes, without advice
Because reliefs that reduce adjusted net income can affect the taper, people near £100,000 often look at pension contributions or Gift Aid in official guidance. Whether any of those steps is right for you is a personal question this site will not answer. What we can say is that the official allowance, limit and £1-for-£2 rule are the same in 2025/26 and 2026/27 on the rates page, and that the return you file for free on GOV.UK is where the real calculation happens. If a later official update changes the limit, that update wins over this guide.
Scottish rates, and a second example in the taper window
Scottish taxpayers lose Personal Allowance under the same official £100,000 limit and the same £1-for-£2 rule. What changes is the rate applied to non-savings, non-dividend income after the remaining allowance is used. In the taper window that income is usually well into the Scottish higher or advanced bands (42% or 45%), and it can reach the top rate of 48% once taxable income after allowances is over £125,141. The informal “60% marginal rate” story that people tell for rUK higher-rate taxpayers therefore does not translate pound-for-pound into Scotland, because the underlying band rates differ. The taper itself is unchanged.
A second example, again labelled as an example, sits in the middle of the window. At £112,570 of rUK employment income the excess above £100,000 is £12,570, so half of that — £6,285 — is taken off the £12,570 allowance, leaving £6,285. Taxable income is £106,285. Income Tax is 20% on £37,700 (£7,540) plus 40% on £68,585 (£27,434), which is £34,974. Compare that with the £27,432 due at £100,000 in the earlier example, and you can see how steeply the bill rises inside the official taper even though the higher rate itself is still 40%.
When you file, use the income and reliefs that belong on the return, not a rounded salary. The official computation of adjusted net income is the one that sets the remaining allowance. Our estimate is a planning figure with the limitations already stated, and it is not tax advice.