Self Assessment: the checklist for sole traders
From registering with HMRC to paying the bill and the payments on account: what to do, in order, and the dates that cost money if you miss them.
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Time: a few hours a year, plus keeping records all year
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Register
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The £1,000 is before you take off expenses or reliefs. Partners in a partnership also have to send a return (GOV.UK).
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With gross trading income of £1,000 or less you may not have to tell HMRC, unless you cannot use the allowance (GOV.UK).
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The tax year runs from 6 April to 5 April. A late registration can bring a penalty (GOV.UK).
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HMRC sends you a UTR. Keep it safe: you need it for every return.
Keep records all year
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Keep invoices, bank statements and payment records (GOV.UK).
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You can only deduct costs that are related to your business, such as office costs, travel, insurance and subscriptions (GOV.UK).
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From 2024 to 2025 the cash basis is the default: you record income when you are paid and costs when you pay them (GOV.UK).
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Money you take from the business for personal use is not an expense (GOV.UK).
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If you filed the 2022 to 2023 return by 31 January 2024, keep the records until at least the end of January 2029 (GOV.UK).
After 5 April: the return
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The difference is your profit, which is what tax is worked out on.
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If you use the allowance you cannot also claim expenses. It helps when your expenses are under £1,000 (GOV.UK).
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Anything untaxed goes on the return too (GOV.UK).
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The online deadline is 11:59pm on 31 January after the end of the tax year. A paper return is due by 31 October (GOV.UK).
Pay the bill
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Class 4 is 6% on profits from £12,570 to £50,270 and 2% above, for 2026 to 2027 (GOV.UK).
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Late payments get penalties and interest (GOV.UK).
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Each payment on account is half of your last Income Tax and Class 4 bill (GOV.UK).
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A balancing payment covers what your payments on account did not (GOV.UK).
Make it easier next year
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The self-employed tax calculator on this site shows how much for your profit.
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HMRC’s Making Tax Digital for Income Tax is a new way to do Self Assessment through software; check on GOV.UK whether it applies to you (GOV.UK).
Return filed and tax paid
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Good to know
- The dates are firm: a late return starts at a £100 penalty, with further penalties after 3, 6 and 12 months. Paying late costs 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest (GOV.UK).
- The first year is the hardest for cash: you pay the whole bill and the first payment on account together, in the same January. If you do not know your profit for the whole year yet, you still have to send a return: GOV.UK explains how.
- If you want to pay your bill through your tax code, you must submit your online return by 30 December (GOV.UK).
- This list is for sole traders. A limited company pays Corporation Tax and its owner is not self-employed, and a partnership has its own return.
- Not tax advice. HMRC and an accountant can answer questions about your situation.
Frequently asked questions
Do I need to do Self Assessment if I am self-employed?
Yes if you were a sole trader and earned more than £1,000 in the tax year, before taking off anything you can claim relief on. Partners in a partnership must also send a return (GOV.UK).
When is the Self Assessment deadline?
For an online return, 31 January after the end of the tax year. A paper return is due by 31 October. You must also pay the tax by 31 January (GOV.UK).
What happens if I miss the deadline?
A late return costs an initial £100. After 3 months there are daily penalties of £10, up to £900. Late payment adds 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest (GOV.UK).
What can I claim as expenses?
Costs of running your business: office costs, travel, clothing such as uniforms, staff costs, stock, insurance and bank charges, premises costs, advertising, subscriptions and training. You cannot claim expenses if you use the £1,000 trading allowance (GOV.UK).
How long do I keep my records?
At least 5 years after the 31 January deadline of the tax year (GOV.UK).
Next step
I’m not an accountant or a financial advisor. This is an estimate, for information only. Check with a professional before you decide.
- The calculatorUK self-employed tax calculator 2026/27
- The short guideSelf Assessment explained: deadlines and payments on account
- The calculatorUK take-home pay calculator 2026/27
- The routeWorking for yourself in the UK
Sources
- GOV.UK — Self Assessment tax returns
- GOV.UK — Self Assessment: who must send a tax return
- GOV.UK — Self Assessment: deadlines
- GOV.UK — Self Assessment: penalties
- GOV.UK — Business records if you’re self-employed
- GOV.UK — Expenses if you’re self-employed
- GOV.UK — Tax-free allowances on property and trading income
- GOV.UK — Self-employed National Insurance rates
- GOV.UK — Understand your Self Assessment tax bill: payments on account
For a complex return, losses, a partnership or a company, ask an accountant or HMRC.