How to pay less tax in the UK — legally
The UK tax system contains several legitimate mechanisms that reduce the amount you pay — not through avoidance schemes, but through the reliefs and allowances parliament has specifically designed for that purpose. Most employed people in their twenties and thirties are not using all of them. This guide explains the main ones, how they interact, and where your biggest opportunities are likely to be.
Before thinking about ways to reduce tax, it helps to understand the baseline. Everyone gets a Personal Allowance of £12,570 — income below this is untaxed. Basic rate tax (20%) applies from £12,570 to £50,270. Higher rate (40%) applies from £50,270 to £125,140. Above £100,000 the Personal Allowance starts to taper, creating a punishing 60% effective rate between £100,000 and £125,140 — the explains this in detail.
In addition to Income Tax, National Insurance applies separately — 8% on earnings between £12,570 and £50,270, and 2% above. The shows exactly how much tax and NI you pay at your current salary.
Pension contributions get Income Tax relief at your marginal rate. A basic rate taxpayer contributing £80 from take-home pay has £100 land in their pension — HMRC adds 20% back automatically. A higher rate taxpayer contributing £60 has £100 land in the pension — and can claim an additional £20 back via self-assessment, meaning the net cost is £60 for £100 in the pension.
If your employer offers salary sacrifice, the saving is even greater — your gross salary is reduced, so you pay less National Insurance too. On a £40,000 salary contributing an extra £200/month via sacrifice instead of standard contributions, the NI saving alone is roughly £288/year. The explains the full mechanics.
The annual pension allowance is £60,000 (or 100% of your earnings if lower). Most employed people are nowhere near this limit, so it's rarely a practical constraint. Use the to see how different contribution rates affect your retirement pot and — via the take-home calculator — what they actually cost you in monthly net pay.
If your employer matches pension contributions above the minimum — contributing more themselves when you contribute more — that matching is the highest-return "tax saving" available. A pound going into your pension via employer match is a pound you didn't earn and didn't pay tax on. Check what your employer will match before looking elsewhere. The covers how to find out.
ISAs don't reduce your tax bill today — but they eliminate tax on future growth and income permanently. Every pound of investment gain inside an ISA is free from Capital Gains Tax. Every pound of interest or dividend income is free from Income Tax. For long-term savers and investors, this compounds into a very significant saving over time.
The £20,000 annual allowance doesn't carry forward — unused allowance is gone at 5 April each year. The shows how much you've used this year and what you'd need to save each month to use the remainder before the deadline.
Basic rate taxpayers can earn £1,000/year in savings interest tax-free. Higher rate taxpayers get £500. Additional rate (45%) taxpayers get nothing. This matters because savings rates have risen significantly — someone with £20,000 in a 5% account earns £1,000/year in interest, which sits exactly at the basic rate allowance. Above that threshold, savings interest is taxed at your marginal rate — which makes a Cash ISA more attractive for larger pots.
When you donate to charity through Gift Aid, the charity reclaims 25% basic rate tax on your donation. If you're a higher rate taxpayer, you can claim the additional relief yourself through self-assessment. A £100 donation costs a basic rate taxpayer £100 (the charity gets £125 in total). It costs a higher rate taxpayer £75 (you reclaim £25 via self-assessment). The relief reduces your adjusted net income, which can also help if you're near the £100k threshold or receiving Child Benefit.
If one partner earns below the Personal Allowance (£12,570) and the other is a basic rate taxpayer, the lower earner can transfer £1,260 of their unused Personal Allowance to their partner — saving up to £252/year in tax. This is called Marriage Allowance and must be actively claimed at gov.uk. It can be backdated up to four years.
Employees can claim tax relief on certain work expenses not reimbursed by their employer — professional subscriptions, tools and equipment, uniforms and PPE, mileage above the employer reimbursement rate. These are claimed through HMRC's online system or via a self-assessment return. The amounts are often modest but the claims are straightforward and frequently not made.
Once earnings exceed £100,000, the Personal Allowance tapers at 50p for every £1 earned above the threshold — creating an effective 60% marginal rate between £100,000 and £125,140. Pension contributions (especially via salary sacrifice) reduce your adjusted net income and can restore the allowance. At this income level, pension contributions are disproportionately valuable — the explains the full mechanics and the numbers.
All of the above are well-established, government-sanctioned ways to reduce tax within the rules. They are not loopholes — they are the reliefs and allowances that parliament created specifically to encourage saving, investment, and charitable giving. Using them is not controversial.
What they are not is advice about your specific circumstances. Someone close to a tax threshold, navigating a complex employment situation, or with significant investment income will find their own picture more nuanced. For anything beyond the basics, a qualified accountant or tax adviser can model the precise numbers for your situation.