The trading allowance, or your expenses?

The trading allowance lets you knock the first £1,000 off your self-employed or casual income before tax. You choose: the £1,000 allowance, or your actual allowable expenses — whichever leaves less to be taxed. Not both on the same income.

Which one wins?

Rule of thumb: if your real costs are under £1,000, the allowance usually wins (and saves you keeping receipts); if they're well above it, claiming actual expenses does. For example, on £18,000 with £6,500 of costs, expenses leave £11,500 to be taxed versus £17,000 with the allowance. These are illustrations, not your numbers — you pick each tax year, and gov.uk or an accountant can confirm your case.

This is general information, not accounting or tax advice — an accountant or HMRC is the right source for your situation.