Tax Year End Checklist: 5 Things to Do Before 5 April 2026

1. Max out your ISA allowance (£20,000)

Every UK adult can shelter up to £20,000 in ISAs each tax year, completely free from income tax and capital gains tax. Once 5 April passes, your unused 2025/26 allowance vanishes — you can't carry it forward.

Even if you can only put away a small amount, it's worth doing. A Cash ISA earning 4.5% on £20,000 generates £900 in tax-free interest per year. Outside an ISA, a higher-rate taxpayer would pay £360 of that to HMRC.

If you're saving for a first home, consider a Lifetime ISA where the government adds a 25% bonus on top (up to £1,000 free per year on a £4,000 contribution).

2. Check your income tax position

The personal allowance for 2025/26 remains at £12,570. If you earn between £100,000 and £125,140, your personal allowance is gradually withdrawn — losing £1 for every £2 earned over £100,000. This creates an effective 60% marginal tax rate.

If you're near the £100,000 threshold: Making a pension contribution before 5 April can bring your adjusted net income below £100,000 and restore your full personal allowance — potentially saving you thousands.

• Personal allowance: £12,570
• Basic rate (20%): £12,571 – £50,270
• Higher rate (40%): £50,271 – £125,140
• Additional rate (45%): Over £125,140

Use our Income Tax Calculator to see exactly where you stand and how a pension top-up could help.

3. Use your capital gains allowance (£3,000)

The capital gains tax-free allowance has been slashed to just £3,000 for 2025/26 (down from £6,000 last year and £12,300 just two years ago). If you have investments with unrealised gains, consider selling enough to use this year's allowance before it resets.

You can immediately reinvest in different holdings — just be aware of the "bed and breakfast" rules that prevent you selling and rebuying the exact same shares within 30 days to crystallise a gain.

4. Top up your pension

You can contribute up to £60,000 into your pension this tax year (or 100% of your earnings, whichever is lower) and receive tax relief. If you haven't used your full allowance from the previous three tax years, you may be able to carry it forward — potentially contributing even more.

For a higher-rate taxpayer, a £10,000 pension contribution effectively costs just £6,000 after tax relief. That's an instant 67% return before any investment growth.

5. Review your expenses if you're self-employed

If you're self-employed or run a side business, make sure you've recorded all allowable expenses for the 2025/26 tax year. Common claims people miss include:

• Working from home allowance (flat rate of £6/week = £312/year)
• Professional subscriptions and memberships
• Business mileage at 45p per mile (first 10,000 miles)
• Phone and broadband (business proportion)
• Training courses related to your current trade

Check our Allowable Expenses Guide for a full breakdown of what you can claim by category.