The £100k "60% Tax Trap" Explained: Keep Your Wealth

Reaching a £100,000 salary is a major career milestone for anyone working in the UK. However, what should be a moment of financial celebration often turns into a nasty shock when the next payslip arrives. Welcome to the infamous "60% tax trap." If you earn between £100,000 and £125,140, you are subject to one of the highest effective marginal tax rates in the country. In this comprehensive guide, we will break down exactly why this happens, the underlying mathematics of the Personal Allowance taper, the devastating impact on childcare benefits, and the fully legal strategies you can use to avoid falling into this trap.

Understanding the Personal Allowance

To understand the 60% trap, we first need to look at the Personal Allowance. For the 2025/26 tax year, the standard UK Personal Allowance is £12,570. This is the amount of money you can earn before you have to pay a single penny of Income Tax. It is a fundamental building block of the UK tax system, designed to ensure that lower earners keep more of their money to cover basic living costs. When you earn less than £100,000, you get to keep this full allowance. The taxman essentially ignores your first £12,570 of income, taxing only what you earn above it at 20% (Basic Rate) and then 40% (Higher Rate) once you cross the £50,270 threshold.

The Taper: How the Trap is Set

The trap springs into action the moment your "Adjusted Net Income" crosses the £100,000 mark. The government decided that high earners shouldn't benefit from the Personal Allowance. So, for every £2 you earn above £100,000, you lose £1 of your Personal Allowance. This is known as the Personal Allowance taper. It is a gradual reduction, but its impact on your take-home pay is brutal. Because you are losing £1 of tax-free allowance for every £2 of extra income, the amount of your income that is subject to tax increases at a faster rate than your actual salary increases.

The Mathematics of 60%

Let's look at a concrete example to see the mathematics in action. Imagine you currently earn exactly £100,000. You are offered a £10,000 pay rise or a £10,000 bonus. Your new gross salary is £110,000.

• Step 1: The 40% Tax. You immediately pay the 40% Higher Rate tax on that extra £10,000. That is £4,000 gone directly to HMRC.
• Step 2: The Lost Allowance. Because your income has increased by £10,000, you lose £5,000 of your Personal Allowance (the £1 for every £2 rule).
• Step 3: Taxing the Lost Allowance. That £5,000 that used to be tax-free is now suddenly taxable at your highest marginal rate, which is 40%. 40% of £5,000 is an additional £2,000 in tax.

Add the £4,000 (from Step 1) and the £2,000 (from Step 3) together, and your total Income Tax bill on that £10,000 pay rise is £6,000. You have just paid 60% tax. Out of your £10,000 raise, you only see £4,000 in your bank account. And that doesn't even factor in National Insurance!

The £125,140 Dead Zone

This tapering continues until your Personal Allowance is completely wiped out. Since the allowance is £12,570, it takes exactly £25,140 of income above £100,000 to reduce it to zero. Therefore, the 60% trap exists strictly within the income band of £100,000 to £125,140. Once you earn £125,141, your Personal Allowance is gone. Any income earned above this point is simply taxed at the Higher Rate of 40% (until you hit the Additional Rate of 45% at £125,140). Paradoxically, this means the marginal tax rate actually drops back down from 60% to 40% once you clear the £125,140 hurdle.

The Childcare Cliff Edge: When 60% Becomes 100%+

For working parents, crossing the £100,000 threshold triggers a secondary, often more devastating financial blow. The government's Tax-Free Childcare scheme (worth up to £2,000 per child per year) and the 15 or 30 hours of free childcare scheme both have a strict cut-off. If your Adjusted Net Income reaches £100,000—even by a single penny—you lose access to these schemes entirely. This is a "cliff edge," not a taper. If a £100 pay rise pushes you over the edge, you could lose £5,000+ in childcare benefits. When you combine the loss of childcare subsidies with the 60% marginal tax rate, the effective tax rate on that extra income can easily exceed 100%. You could literally end up poorer by getting a pay rise.

Strategies to Escape the Trap

Fortunately, the taper is based on "Adjusted Net Income," not your raw gross salary. You can legally reduce your Adjusted Net Income to keep it below £100,000.

1. Pension Contributions (Salary Sacrifice)

This is the most popular and effective method. By funneling the portion of your salary that falls into the trap (e.g., the £10,000 in our previous example) into your pension via Salary Sacrifice, you reduce your Adjusted Net Income back to £100,000. You completely avoid the 60% tax, you keep your Personal Allowance, you preserve your childcare benefits, and you build your retirement wealth with money that would have otherwise gone to the taxman. It is a massive financial win.

2. Charitable Donations (Gift Aid)

If you don't want to lock the money away in a pension, donating to charity through Gift Aid also reduces your Adjusted Net Income. While you are giving the money away, the tax efficiency makes the actual cost to you significantly lower than the amount the charity receives.