Reducing Your Tax Through Pensions

Pension contributions don't just build up money for later, for some earners, they're also a particularly effective way to cut this year's Income Tax bill. That's especially true if you're caught in the 60% tax trap, where the numbers work out unusually well in your favour. This page explains why, with a worked example.

The short version

Paying into a pension reduces a figure called your adjusted net income, not the same thing as your salary or your taxable pay. If that reduction brings you back under £100,000, you stop losing Personal Allowance to the taper altogether, on top of the normal tax relief you'd get on any pension contribution. Below £100,000 (or above £125,140, where the taper's already finished), a pension contribution is still worthwhile, just not unusually so.

Why pension contributions are different from other deductions

Most of what comes off your pay, i.e. Income Tax, National Insurance, is calculated on your salary and stays there. A relief-at-source pension contribution (the method covered on the Salary Calculator page, and the most common one) behaves differently: it's taken from your pay after Income Tax and National Insurance are already worked out, so it has no effect on either of those calculations directly.

What it does affect is your adjusted net income, a separate figure HMRC uses specifically to test a handful of income-based thresholds, the £100,000 Personal Allowance taper among them. A relief-at-source contribution reduces adjusted net income by its full grossed-up value, what actually left your pay, plus the basic-rate tax relief your pension provider claimed back and added on top, not just the smaller amount deducted from your payslip.

That distinction is what makes pension contributions unusually powerful specifically in the £100,000–£125,140 band: they don't touch the Income Tax calculation on your payslip, but they can still switch the taper off.

Worked example: escaping the 60% tax trap

Say you earn £110,000 a year, squarely inside the tax trap band. Without any pension contribution, here's where you stand — the same figures worked through in full on the 60% tax trap page:

Personal Allowance, after the taper: £7,570 (down from the standard £12,570)
Income Tax due: £33,432
Take-home pay: £72,357.40

Now say you pay £8,000 into a relief-at-source pension this year.

Taken from your pay: £8,000
Grossed up by your pension provider (÷ 80%, the same relationship used throughout the Salary Calculator worked example): £8,000 ÷ 0.8 = £10,000 lands in your pension pot, including £2,000 of basic-rate relief added automatically.
That £10,000 is also how much your adjusted net income falls by, from £110,000 down to exactly £100,000, right at the taper threshold.
With adjusted net income no longer above £100,000, the taper switches off completely. Your Personal Allowance is restored to the full £12,570.
Income Tax, recalculated with the full allowance: £31,432. (£2,000 less than before.)
Take-home pay: £66,357.40 (£6,000 less than before), and £10,000 in your pension for a total benefit of £76,357.40.

Put another way: taking £8,000 out of your pay only cost you £6,000 of take-home pay, because £2,000 of it came back as extra Income Tax you no longer owed. For that £6,000, £10,000 landed in your pension pot. National Insurance is unaffected either way, relief-at-source contributions don't touch it, in this band or any other.

Why this is worth more than ordinary pension tax relief

Every pound of adjusted net income you bring down from above £100,000 to at or below it is doing two things at once: escaping the 40% higher rate that pound would otherwise be taxed at, and rebuilding the Personal Allowance the taper is otherwise stripping away, 50p of allowance for every £1 over the threshold. That's the same mechanism behind the 60% tax trap itself, just running in reverse. See The 60% Tax Trap for how the taper builds up in the first place.

Once your adjusted net income drops to £100,000 or below, that particular boost is used up. You're out of the taper band, and further contributions get you the same tax relief anyone else would get at their normal marginal rate, no more.

Things to know before doing this

This only covers relief-at-source contributions. Net pay arrangement and salary sacrifice pensions change these numbers differently. They reduce your taxable pay directly, rather than adjusted net income after the fact. See Your Pension Contributions Explained for how those compare.
The Annual Allowance still applies. You can normally pay up to £60,000 into pensions in a tax year before an annual allowance charge potentially kicks in (less if you're a very high earner, or more if you have unused allowance carried forward from previous years). See gov.uk's guidance on unused annual allowances.
The money is locked away. Unlike a straightforward tax deduction, pension contributions aren't accessible again until you're old enough to draw your pension (currently 55, rising to 57 from 2028). This is a genuine trade-off, not just a tax calculation.
This isn't the only threshold pension contributions affect. Adjusted net income is also what's tested for the High Income Child Benefit Charge, a different band (£60,000–£80,000), lower down the income scale, but reduced by pension contributions the same way.
This page is about going beyond the legal minimum. If you're not sure whether you're even enrolled, or what the statutory minimum actually is, start with Workplace Pension Auto-Enrolment Explained. Everything above assumes you're already contributing and asks whether contributing more makes sense.

This page explains general rules for reducing tax through pension contributions and is not personalised advice; see the disclaimer. Deciding how much (if anything) to pay into a pension depends on your full circumstances, including whether you can afford to have that money locked away; speak to a qualified financial adviser before making decisions.