UK Personal Allowance Taper: The £100,000 Tax Trap 2026/27
How the £12,570 Personal Allowance is withdrawn by £1 for every £2 of adjusted net income above £100,000, producing a 60% effective marginal Income Tax rate for many taxpayers between £100,000 and £125,140.
Key Statutory Takeaways
Statutory Rules & Core Thresholds
Personal Allowance: £12,570. Taper threshold: £100,000 (withdrawn at £1 per £2 of excess). Fully withdrawn at £125,140 (60% effective marginal rate).
In-Depth Legal Framework & Analysis
Under Section 35 of the Income Tax Act 2007, an individual's standard Personal Allowance (£12,570 for 2026/27) is reduced by £1 for every £2 by which their adjusted net income exceeds £100,000. For an individual in England, Wales, or Northern Ireland paying the 40% higher rate, each £100 of income in the taper band suffers £40 direct income tax while losing £50 of tax-free allowance (which creates an additional £20 tax charge), creating an effective 60% marginal tax rate. In Scotland, higher devolved rates (42% Higher and 45% Advanced) mean the effective rate can reach up to 63% or 67.5%. Adjusted net income is calculated after deducting gross qualifying pension contributions and Gift Aid donations grossed up by 1.25.
PAYE coding adjustments occur automatically. If a Self Assessment return is required for other untaxed income, the deadline is 31 January.
Failure to notify HMRC of untaxed income pushing adjusted net income over thresholds triggers formal compliance enquiries, P800 underpayment notices, statutory interest, and penalties.
How the £100,000 Taper Works
Personal Allowance = £12,570 - ((adjusted net income - £100,000) ÷ 2)| Adjusted Net Income | Personal Allowance Remaining |
|---|---|
| £100,000 | £12,570 |
| £110,000 | £7,570 |
| £120,000 | £2,570 |
| £125,140 | £0 |
📉 Why the Effective Rate Can Be 60%
For an England, Wales or Northern Ireland taxpayer whose marginal rate is 40%, each additional £1 of adjusted net income between £100,000 and £125,140 produces £0.40 of direct Income Tax and removes £0.50 of Personal Allowance.
Frequently Asked Questions: UK Personal Allowance Taper: The £100,000 Tax Trap 2026/27
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Primary Statutory Authority
Frequently Asked Questions
For 2026/27, the standard £12,570 Personal Allowance is reduced when adjusted net income exceeds £100,000. It falls by £1 for every £2 above £100,000 and reaches zero at £125,140.
For an England, Wales or Northern Ireland taxpayer paying the 40% higher rate, each extra £1 above £100,000 creates 40p of Income Tax and removes 50p of Personal Allowance. Losing that 50p allowance adds another 20p of tax at the 40% rate, producing a 60p effective tax cost.
No. The Personal Allowance taper is based on adjusted net income. This can include salary and taxable benefits as well as pension income, savings interest, dividends, rental income and foreign income, with certain deductions such as qualifying pension contributions and Gift Aid reducing the figure.
Yes. Qualifying pension contributions can reduce adjusted net income for the taper calculation, subject to the pension tax rules. This means a contribution can potentially preserve some or all of the Personal Allowance as well as providing pension tax relief.
No. The separate Self Assessment income threshold for PAYE-only taxpayers was removed from 2024/25 onward. You may still need to file for other reasons, such as untaxed income, certain capital gains, self-employment, partnership income or other HMRC filing requirements.
No. The Personal Allowance is tapered using the same £1-for-£2 formula, but Scottish taxpayers use Scottish Income Tax rates on non-savings and non-dividend income. Because some Scottish marginal rates are 42% or 45%, the effective marginal impact of losing the allowance can exceed 60% in the relevant bands.
Common Taxpayer Misconceptions
✓ Rule: The PAYE-only Self Assessment income threshold was removed from 2024/25 onward. Income above £100,000 alone does not automatically require a return.
✓ Rule: The 60% calculation applies where the taxpayer's marginal rate is 40%. The effective rate differs for Scottish taxpayers subject to higher Scottish rates (42% and 45%).
✓ Rule: The taper uses adjusted net income, which can include employment, pension, dividend, savings, rental and foreign income and is reduced by specified reliefs like gross pension contributions and Gift Aid.