Self Assessment for freelancers

Register, file, pay

1. Register for Self Assessment if your gross trading income is over £1,000 in a tax year. Deadline to tell HMRC is 5 October after that year ends (5 October 2026 for 2025/26).
2. Keep income and expense records as you go. HMRC can ask for them for at least five years after the 31 January filing deadline.
3. File the online return by 31 January 2027 for 2025/26 (paper was 31 October 2026). Pay the balancing payment the same day.
4. If last year’s bill was over £1,000, Payment on Account is due 31 January and 31 July, each 50% of that bill.

Full deadline calendar and penalty ladder.

What goes on the self-employment pages (SA103)

Turnover is invoices paid (cash basis) or invoiced (accruals). Do not use the bank balance. Expenses: software, office, motoring, other. If you have PAYE, complete the employment pages too. Student loan repayments are not an expense of the trade; they are collected through the return or PAYE separately.

Deadlines and penalties

Miss the online deadline and the late-filing penalty is £100 immediately, even if you owe no tax. After three months it is £10 a day (capped at £900). At six and twelve months HMRC add 5% of the tax due or £300, whichever is greater. Late payment is a separate 5% at 30 days, six months and twelve months, plus interest.

Mistakes freelancers make on the return

• Using drawings (money you transferred to yourself) as if they were expenses.
• Forgetting foreign-currency invoices or counting them at the wrong rate.
• No working paper for the home office percentage.
• Missing Payment on Account after the first decent year.
• Not signing up to MTD software when gross income already required it from April 2026.

Retainers feel like a salary. They are not PAYE unless the client puts you on payroll. Put 25–30% of each invoice aside on the day it lands. Waiting for a quiet month is how January happens to people who “meant to”.

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