The £100k Personal Allowance Taper Explained: Impact on Take-Home Pay

Why the £100k to £125,140 range matters

As income rises above £100,000, personal allowance is reduced, which increases effective deductions on that slice. This catches many people by surprise when pay rises feel less valuable than expected.

The effect is often described informally as a high effective deduction zone. Whether this is temporary or persistent for you depends on salary structure, bonus pattern and pension strategy.

For planning, it is essential to compare multiple scenarios rather than relying on one headline estimate.

• Allowance reduction changes effective deductions.
• Pay rises in this range can feel smaller in net terms.
• Scenario planning is essential for realistic decisions.

How to model this range correctly

Use salary points across the range, such as £100k, £110k, £120k and £125k. Compare monthly net delta between each point, not only annual totals.

Then test pension contribution changes. For many employees, pension choices materially alter taxable pay and therefore the shape of net outcomes in this range.

If variable bonus is likely, include conservative and optimistic bonus cases. This avoids overestimating stable monthly cashflow.

• Model at several salary points, not one.
• Include pension scenarios explicitly.
• Use monthly net deltas for decisions.

Decision framework for offers near six figures

When choosing between offers near this boundary, compare package structure as well as gross value. A slightly lower gross offer with stronger pension support may produce better long-term outcomes.

Use a transparent checklist: salary, expected bonus reliability, pension design, student loan status and tax code. Without this, comparisons are often inconsistent.

The strongest negotiations are grounded in net-pay evidence. Showing realistic monthly deltas is usually more persuasive than discussing gross salary in isolation.

• Compare structure, not just headline gross salary.
• Use the same assumptions for every offer.
• Base negotiation on monthly net evidence.

A threshold-aware offer review template

At higher salaries, small gross changes can produce smaller-than-expected monthly gains. A threshold-aware model helps set realistic expectations.

Track net monthly delta and effective deduction change together to understand the true value of progression decisions.

• Measure net monthly delta, not gross only.
• Track effective deduction shifts between scenarios.
• Document assumptions for negotiation discussions.

The personal allowance taper: exactly how it works

The personal allowance (£12,570 in 2026/27) is withdrawn at a rate of £1 for every £2 of adjusted net income above £100,000. Adjusted net income is gross income less pension contributions and gift aid donations. The allowance is fully removed at £125,140 (£100,000 + 2 × £12,570). Between £100,000 and £125,140, each £2 of additional income loses £1 of tax-free allowance, which is then taxed at 40%, creating an effective 60% marginal rate in this band (40% on the income itself + 20% effective rate on the allowance withdrawn and taxed at 40%).

To calculate the extra tax from taper: if your salary rises from £100,000 to £102,000 (£2,000 increase), the taper withdraws £1,000 of personal allowance. That £1,000 of formerly tax-free allowance is now taxed at 40% = £400 extra tax. Plus the income tax on the new £2,000 income itself at 40% = £800. Total extra income tax = £1,200 on a £2,000 gross rise. After NI (2% on the rise above upper earnings limit) of £40, take-home gain = £2,000 − £1,200 − £40 = £760. That is 38p take-home per £1 of gross increase.

At £125,140, the full allowance has been withdrawn. Above this level, the effective marginal rate returns to 45% (additional rate) plus 2% NI = 47%. While this is still high, the effective rate is actually lower than the taper range (60%). This is counterintuitive, earning more above £125,140 actually keeps you a higher percentage per pound than earning in the £100,001–£125,140 range.

• Taper range: £100,000–£125,140, allowance reduced by £1 per £2 of income.
• Effective marginal rate in taper: 60% (income tax 40% + allowance clawback 20%).
• Above £125,140: effective rate drops to 47% (45% tax + 2% NI).
• 38p take-home per £1 of gross in taper range vs 53p above £125,140.

Using pension salary sacrifice to manage the taper

Pension salary sacrifice (and personal pension contributions via self-assessment) reduce adjusted net income, the figure HMRC uses to calculate personal allowance. If your adjusted income is £110,000 and you sacrifice £10,000 into your pension, adjusted net income drops to £100,000 and the taper does not apply. The personal allowance is fully restored, saving approximately £5,028 in income tax (£12,570 × 40%).

For a salary of £120,000, reducing adjusted income below £100,000 would require contributions of £20,000, potentially beyond annual allowance limits. The pension annual allowance is £60,000 for most individuals in 2026/27, so a £20,000 contribution is within limits for most people. However, tapered annual allowance can reduce this for very high earners (those with adjusted income above £260,000).

Even partial restoration of the allowance is valuable. Reducing adjusted income from £115,000 to £110,000 (a £5,000 pension contribution) recovers £2,500 of personal allowance (£5,000 / 2). That £2,500 recovers from being taxed at 40%, saving £1,000 in income tax. The pension contribution itself is also tax-sheltered, so the combined value of the £5,000 contribution is: tax on income avoided (40% × £5,000 = £2,000) plus allowance restored (£1,000) = £3,000 total tax saving on a £5,000 pension contribution. Effective cost of contributing £5,000: £2,000.

• Pension contributions reduce adjusted net income, restoring lost personal allowance.
• Restoring £12,570 allowance saves approximately £5,028 in income tax.
• £5,000 pension contribution in taper range saves approximately £3,000 in tax.
• Annual pension allowance is £60,000 in 2026/27 (lower for very high earners).