The Ultimate Checklist for Tax Year End: 10 Things to Do Before 5 April

The tax year ends at midnight on 5 April, and any allowance you have not used by then simply disappears. There is no carry-over for your ISA, no grace period for the capital gains exemption, and no second chance on the pension contribution you meant to make in February. The reassuring part is that a focused evening or two before the deadline can save you hundreds, sometimes thousands, of pounds. Here is what to work through, roughly in order of how much it tends to matter.

Use your full ISA allowance

Every adult can put up to £20,000 into ISAs each tax year, and the allowance resets on 6 April rather than rolling over. Interest, dividends and gains inside an ISA are free of UK tax, so anything left unused is shelter you have paid for and not claimed.

Do not assume the money has to be new savings. Moving existing cash, or selling investments and rebuying them inside an ISA, still shelters the future growth. If you are selling assets to fund the ISA, remember that the disposal itself can trigger a capital gain, and the share matching rules can catch you out if you buy the same investment back within 30 days.

Smaller pots that share the same limit

A Lifetime ISA accepts up to £4,000 a year and adds a 25% government bonus, but it counts towards your £20,000. You can open one between 18 and 39 and keep contributing until you turn 50. Junior ISAs allow £9,000 per child, and a grandparent or family friend can pay in without using their own allowance. The contribution deadline is the same: 5 April.

Top up your pension, and check what you have already used

Pension contributions attract tax relief, which makes them one of the most efficient places for spare money to land. Most people can contribute up to £60,000 across all their pensions in a tax year, capped at 100% of their earnings, and unused allowance from the previous three years can often be carried forward.

Two practical points are easy to miss. First, the money usually needs to reach your provider before 5 April — a bank transfer that arrives on 6 April is too late. Second, if you have already flexibly accessed a defined contribution pot, or your income is high enough to taper your allowance, your limit will be lower. Check the current figures on GOV.UK before you assume anything.

Higher and additional rate taxpayers normally need to claim the extra relief through Self Assessment or by asking HMRC to adjust their tax code. Basic rate relief is usually claimed by the provider automatically.

Sort out capital gains before the deadline

The annual exempt amount for capital gains tax is currently £3,000 per person, and it cannot be carried forward. If you have investments sitting on a gain and you plan to sell at some point anyway, realising some of it before 5 April can use up this year's exemption rather than wasting it.

• Use both allowances. Transfers between spouses and civil partners are treated as no gain, no loss, so assets can be moved so that two exemptions are available.
• Claim your losses. Losses can be offset against gains, and unused losses must be reported within four years of the end of the tax year. Report them even in a year when you owe nothing.
• Watch the 60-day rule. Sales of UK residential property with a gain usually need reporting and payment within 60 days of completion, whatever the time of year.
• Keep your records. Contract notes, purchase dates, costs and improvement spending are all needed to work out the gain correctly.

CGT rates depend on your income and the type of asset sold, so check the current rates or ask an accountant before you bank on a particular figure.

Mop up the allowances people forget

Beyond ISAs and pensions there is a cluster of smaller reliefs that quietly expire each April:

• Dividend allowance. Only a small amount of dividend income is tax-free each year. If you control when dividends are paid, deferring one until after 5 April can use next year's allowance instead.
• Personal savings allowance. Basic rate taxpayers receive £1,000 of interest tax-free, higher rate taxpayers £500, and additional rate taxpayers nothing. ISAs remain the cleaner home for larger cash balances.
• Trading and property allowances. £1,000 each, useful if you have a small side income or rent a room informally.
• Marriage allowance. If one partner earns below the personal allowance, they can transfer part of it to a basic rate taxpayer partner, worth roughly £250 a year.
• Gift Aid. Donations made under Gift Aid let higher rate taxpayers reclaim the difference, and they extend your basic rate band, which can reduce tax on dividends and gains.
• Inheritance tax gifts. £3,000 of exempt annual gifting per person, plus small gifts of up to £250 per recipient, resets on 6 April.
• Job expenses. Professional subscriptions, uniform costs and mileage can be claimed for up to four previous tax years.

Check your paperwork, tax code and payments

Pull together your P60, your most recent payslips and any P11D from a previous employer, then check your tax code against HMRC's records. Errors are common and usually work in HMRC's favour, not yours.

If you are newly self-employed or need to file a return for the first time, you generally have to register with HMRC by 5 October following the end of the tax year. The filing and payment deadline is 31 January, with a second payment on account due on 31 July. If either partner's adjusted net income sits between £60,000 and £80,000, part of any Child Benefit is clawed back, and pension contributions or Gift Aid donations can bring that figure down.

Your final-week checklist

1. Log in to every ISA and pension account and note what you have paid in this year.
2. Decide the amount you can realistically add before 5 April, and make the payment early enough to clear.
3. Review your investment portfolio for unrealised gains and losses.
4. Claim any unused capital losses, even if you have no gain to offset this year.
5. Check whether a Bed and ISA transfer makes sense for holdings outside an ISA.
6. Confirm your tax code and claim any expenses you are owed.
7. Make Gift Aid donations and record them, particularly if you pay higher rate tax.
8. Use the inheritance tax gifting exemption if you were planning to help family members.
9. File the paperwork somewhere you will find it next year — a folder or a cloud note is fine.

Get it done before 5 April

Start with the two big ones. Funding an ISA and topping up a pension will usually do more for your tax bill than anything else on this list, and they are the allowances with the least wiggle room once the deadline passes. Then work down through capital gains and the smaller reliefs as time allows.

Do not leave it all to the final afternoon. Providers get busy, bank transfers can be delayed, and websites have a habit of struggling on 5 April. Set aside an hour this week, gather your account numbers and statements, and make a list of the decisions you need to take.

If your affairs are more complicated — a business, rental property, share schemes or overseas income — it is worth speaking to an accountant or a regulated financial adviser. Tax rules change, and the right answer genuinely depends on your circumstances.

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