Tax Year End Crypto Checklist for UK Investors: What to Sort Before 5 April

Most crypto tax problems are not created in January. They are created in the quiet weeks before the tax year ends, when a five-minute decision about one sale, one wallet or one missing CSV would have fixed everything. The UK tax year closes on 5 April. After that, the gains, the losses and the paperwork for the year are largely locked in.

This is the checklist to work through now, while there is still time to act rather than just report.

Know which deadlines actually matter

The 5 April date is only the first of several. Confusing them is how people end up filing late or missing a claim they were entitled to make.

• 5 April — the tax year ends. This is the last day on which a disposal counts towards the current year's gains and losses.
• 5 October — deadline to register for Self Assessment if you need to file a return for the first time.
• 31 October — deadline for a paper return.
• 31 January — deadline for the online return and for paying the tax due.

There is a separate rule worth knowing: if you want to use a loss in a future year, you generally need to notify HMRC within four years of the end of the tax year in which it arose. Losses do not quietly look after themselves.

Use your capital gains allowance deliberately

Capital gains tax only bites when something is disposed of. In crypto, that covers more ground than most people expect: selling for pounds, swapping one token for another, spending crypto on goods or services, and gifting it (except to a spouse or civil partner, where special no-gain, no-loss treatment usually applies). Moving coins between your own wallets is not a disposal; trading one asset for a different one is.

The annual exempt amount lets you realise a certain level of gains without paying capital gains tax. It has been £3,000 in recent tax years, and it is per person, not per household — so check the figure applying to your year on GOV.UK rather than relying on memory.

The sensible use of it is straightforward. If you already plan to sell part of a holding, timing that sale before 5 April can use up allowance you would otherwise waste. What is less sensible is selling an asset you want to keep purely to "use up" the allowance. You would trigger a real disposal, reset your base cost and take on the job of getting back in at a sensible price. If you do want to rebuy, remember the 30-day matching rule below — it can undo the plan entirely.

Harvest losses, but respect the 30-day rule

If you are sitting on an asset that has fallen, selling it crystallises a loss. That loss can be set against gains in the same year, reducing the tax bill, and any excess can generally be carried forward.

The trap is the matching rule. HMRC applies the same-day and 30-day identification rules used for shares to cryptoassets. If you sell a token at a loss and buy the same token back within 30 days, the repurchase is matched with the sale, which can mean the loss you thought you had banked is not available in the way you expected. Either wait out the 30 days or do not build a plan around an immediate rebuy.

Two further points. Crypto losses can only be set against capital gains, not against salary or other income. And if you have a loss but no gains this year, you may still need to report it if you want to use it later.

Get your exchange statements before you need them

Platforms close. They merge, restrict access by jurisdiction, change their CSV exports or quietly stop showing older trades in the interface. The transaction history you can download today may not be available next spring.

Do this for every exchange, staking platform, lending service and wallet you have used, including the ones you barely touch. Export the full transaction history as CSV and save a PDF statement where the platform offers one. Then check the export properly: does it go back to your first trade, does it include fees, and does it show what each asset was swapped for? If something is missing, take screenshots now and note what is absent while you can still see the data on screen. For on-chain activity, pull transaction lists from a block explorer and save those too.

Build a record set that answers the obvious questions

A spreadsheet is enough, as long as it can be reconciled back to statements. For each transaction, capture:

• Date and, where you have it, the time
• Asset and amount
• The pound value at the time, from a consistent source
• Whether it was a buy, sell, swap, spend, gift or income receipt
• Fees paid, and which exchange or wallet was involved

Keep the underlying statements alongside it, and back the whole folder up in two places. HMRC expects records to be kept for at least five years after the filing deadline for the year in question. A consistent valuation source matters more than a perfect one; switching between methods halfway through the year creates work you will resent later.

Do not forget income events

Staking rewards, airdrops, mining, interest from lending platforms and crypto received as payment for work or goods are generally treated as income, taxed at your marginal rate. The pound value when you received it becomes income, and that same value usually becomes your base cost for capital gains purposes when you later dispose of it. This is the detail people miss, and it can affect two tax calculations from one transaction.

The £1,000 trading allowance can reduce some small amounts of miscellaneous income, but the conditions are specific. Check before assuming it applies.

A workable plan for the final few weeks

Block two hours this week and work through this in order:

1. Export statements and transaction history from every platform and wallet you have used.
2. Reconcile everything into one sheet, with a row per disposal.
3. Total your gains and losses for the year so far.
4. Decide, calmly, whether any further disposals before 5 April are genuinely worth making.
5. List income events separately from disposals.
6. Diary the filing deadlines and back up the records.

Then leave it alone. Tax should inform a decision you were already inclined to make, not push you into a trade you would not otherwise place. If your activity involves a lot of DeFi, many wallets, or a volume of trading that might be viewed as a business rather than investing, speak to an accountant who handles cryptoassets. General guidance is a starting point, not a substitute for advice on your own circumstances.

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