Self Assessment guide for UK freelancers
A plain-English walk through the Self Assessment process for sole traders and freelancers, with the dates that matter.
The seven steps
- 01
Register with HMRC
If this is your first year self-employed, register for Self Assessment by 5 October following the end of the tax year. You will get a Unique Taxpayer Reference (UTR) by post. Keep it safe.
- 02
Gather your records
Pull together every invoice you issued, every business expense receipt, mileage logs, bank statements and any other income, such as interest, dividends or an employment P60.
- 03
Calculate your turnover
Total up all the invoices you issued for work done in the tax year, 6 April to 5 April. This is your gross self-employment income, box 9 on the SA103S.
- 04
Add up allowable expenses
Only costs that are wholly and exclusively for the business count: materials, software, travel, mileage at the approved rates, a fair share of home office costs, professional fees. Keep receipts for six years.
- 05
Work out your net profit
Turnover minus allowable expenses is your net profit. This is what gets taxed.
- 06
Calculate the tax owed
The personal allowance, £12,570 for 2025/26, is tax free. Above it you pay 20 percent at the basic rate, 40 percent at the higher rate and 45 percent at the additional rate, plus Class 4 National Insurance. Class 2 is voluntary above the small profits threshold. Student loan repayments apply if you have one. The free tax calculator works it out for your own profit.
- 07
File and pay by 31 January
Submit online and pay any tax owed by 31 January after the tax year ends. If you owe more than £1,000 you also make payments on account: half of next year’s estimated bill, in advance.
Key dates
| Date | What | Who |
|---|---|---|
| 5 October | Register for Self Assessment | If it is your first year |
| 31 October | Paper return deadline | If you file on paper |
| 31 January | Online return and payment | File online and pay the tax owed |
| 31 July | Second payment on account | If payments on account apply |
Common allowable expenses
- Office supplies and stationery
- Business software subscriptions
- Phone and broadband, the business share
- Mileage at the HMRC approved rates
- Accountancy fees
- Professional indemnity insurance
- Marketing and advertising
- Bank charges on business accounts
- Training that maintains existing skills
- Home office flat rate or a proportion of costs