Key takeaways
- Register for Self Assessment by 5 October after the tax year ends.
- File online by 31 January and pay what you owe by the same day.
- You report self-employment income (the money from your invoices) minus allowable expenses.
- Keep records for at least 5 years after the 31 January deadline — 6 if you're VAT-registered.
- A full box of jobs below £1,000 is covered by the trading allowance, but anything above that means registering.
Do you need to register at all?
You need Self Assessment if you are self-employed and earned more than £1,000 from self-employment in a tax year. There's a £1,000 "trading allowance" that keeps tiny sidelines out of the system entirely, but the moment your gross receipts pass that, you should register with HMRC. This applies whether you're billing under your own name as a sole trader or you simply have a side income alongside a job.
If the income is from a limited company you own, it's different: your company pays Corporation Tax and files its own accounts, and you report salary and dividends to HMRC separately. The solo, self-employed route is what Self Assessment is for.
5 October — register
After the tax year ends on 5 April, you have until 5 October to register for Self Assessment online. Do it early — it's free, quick, and you'll get a Unique Taxpayer Reference (UTR) that you need for everything after.
31 October — paper return (if you insist)
If you file on paper, the deadline is 31 October after the tax year. Almost nobody should do this — the online route is easier, more accurate and gives you three extra months.
31 January — file online and pay
The one that matters: 31 January. File your online return and pay any tax you owe by the same date. If the system shows you have tax due, it's due then too — plus, for most first-timers, a "payment on account" of half of next year's estimated bill.
What you report: income and expenses
Your return is built from a simple formula: income − allowable expenses = taxable profit, and tax is charged on that profit. For a freelancer:
- Income: everything you invoiced and received for your work — whether the client paid in cash, by transfer or in kind. Unpaid invoices you eventually write off a still a story for your accountant, but the starting point is simple: what came in.
- Expenses you can claim: office costs, software and subscriptions you use for the work, travel that's specifically for the business, a business proportion of your home phone and internet, insurance, professional fees and bank charges.
- The catch: HMRC only accepts costs "wholly and exclusively" for the trade — a general webcam isn't claimable, but the one you bought to shoot client videos is.
Because your invoices are the spine of your Self Assessment, keeping them tidy is not cosmetic. What you invoice becomes what you declare. Our templates are designed so the summary at the bottom mirrors what goes on the return.
Records to keep (and for how long)
Keep every sales invoice, every receipt for a business expense, and any record of money you've taken out of the business. The rule of thumb: keep records at least 5 years from the 31 January deadline of the tax year — so for the 2025/26 year, that's until January 2032. If you're VAT-registered, it's 6 years, and HMRC can ask for records up to 6 years back in some cases.
Digital copies are fine — HMRC accepts them. The PDF you download from your invoice tool or a folder of scanned receipts is exactly what you need if you're ever checked.
Keep your invoicing ready for the return
A compliant UK invoice with a clean total — free, no sign-up, nothing uploaded.
Frequently asked questions
When is the Self Assessment deadline for freelancers?
Register by 5 October, file online by 31 January, and pay any tax due by 31 January. Paper returns are due by 31 October.
Do I need to register for Self Assessment as a sole trader?
Yes — if you earn more than £1,000 from self-employment in a tax year. Registering is free and gives you a UTR.
What expenses can a freelancer claim?
Office costs, work software, business travel, a home-office proportion of bills, insurance and professional fees — only the business proportion of costs wholly and exclusively for your trade.
How long must I keep invoices and records?
Usually 5 years from the 31 January deadline of the relevant tax year; 6 years if VAT-registered.
What happens if I miss the 31 January deadline?
You get a late-filing penalty (from £100), and interest builds on any tax paid late. Filing a day early is better than a day late.
Is Self Assessment the same as limited company tax?
No. Self-employed freelancers use Self Assessment; a limited company files accounts with Companies House and pays Corporation Tax, and its directors report salary and dividends separately.
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General guidance only — this is not legal, tax or accounting advice. Deadlines and allowances can change in a Budget. Last reviewed 23 September 2026.