How to Rescue Your Income from the £100k Cliff Edge

In the UK, we are told the “Additional Rate” of tax is 45%. But for a specific group of professionals and high-earners, there is a hidden “Tax Trap” where the effective rate hits 60% (and that’s before you even factor in National Insurance).

If your income is between £100,000 and £125,140, this is the most important financial article you will read this year.

1. Why does the “Trap” exist?

The trap is caused by the withdrawal of the Personal Allowance.

Normally, the first £12,570 you earn is tax-free. However, for every £2 you earn over £100,000, you lose £1 of that allowance. By the time you hit £125,140, your tax-free allowance is gone entirely.

The Math of the Trap:

• You pay 40% income tax on that extra £2.
• You lose £1 of your tax-free allowance, which is now taxed at 40%.
• Result: On that £2, you’ve paid 80p + 40p = £1.20 in tax.
• That is an effective tax rate of 60%.

2. The Pension “Escape Hatch”

The good news? HMRC calculates this trap based on your Adjusted Net Income. By making a pension contribution, you lower that figure and “pull” yourself back below the cliff edge.

Case Study: The £110,000 Earner

• Scenario A (Do Nothing): You earn £110k. You are £10k into the trap. You pay £6,000 in tax on that top £10k slice. You take home £4,000.
• Scenario B (The Pension Move): You put that £10,000 into your SIPP or workplace pension.
  • Your “Adjusted Income” drops to £100,000.
  • Your full £12,570 Personal Allowance is restored.
  • The Result: The full £10,000 goes into your retirement pot, but it only “costs” your take-home pay £4,000.

Money Simplified Tip: HMRC is essentially offering you a “Buy one, get one and a half free” deal on your retirement. You put in £4,000 of take-home pay, and they top it up to £10,000. You won’t find those returns on the stock market.

3. The “Hidden” Dangers of Crossing £100k

The 60% tax isn’t the only penalty for hitting six figures. Crossing the £100,000 threshold also triggers:

• Loss of 30 Hours Free Childcare: If one parent earns £100,001, you lose eligibility for free childcare and the Tax-Free Childcare scheme (worth up to £2,000 per child). This can make your effective tax rate over 100% for that extra pound of earnings.
• Self-Assessment Requirement: You are legally required to file a tax return once you hit this threshold, even if all your tax is usually paid via PAYE.

4. How to Execute the Move

1. Calculate your “Adjusted Net Income”: This is your total taxable income minus things like gift aid donations and pension contributions.
2. Check your “Carry Forward”: If you earn £120,000 and want to contribute £20,000 to clear the trap, ensure you have enough Annual Allowance left (refer to our Month 5 Guide).
3. Time it Right: Most people make these “mop-up” contributions in March, just before the tax year ends on April 5th, once they have a final view of their total annual earnings and bonuses.

Summary: The "Save Your Allowance" Checklist

• Total up your expected salary, bonuses, and taxable benefits (like car allowances).
• Identify how far you are over the £100,000 mark.
• Use a pension contribution to bring your "Adjusted Net Income" back down to £100,000 exactly.
• Re-claim your 30 hours of free childcare (if applicable).