What records do I need to keep as a self-employed sole trader?

You need to keep records of every business sale and expense, bank statements, invoices you've issued and received, and evidence for anything you're claiming as an allowable cost — and you're required to keep them for at least five years after the 31 January submission deadline for that tax year.

HMRC doesn't need to see these when you file, but they can ask for them if they open a check into your return, and if you can't produce the evidence, they can disallow the expense and adjust your tax bill upwards. Digital records kept in accounting software rather than a shoebox of receipts make this far less painful if HMRC ever does ask, and from April 2026 keeping digital records becomes mandatory anyway once you're in scope for Making Tax Digital. If you're still keeping records on paper or in scattered spreadsheets, it's worth moving to something structured before HMRC — or your own year-end — forces the issue.