Self Assessment checklist for sole traders
The return is easier when the records are ready before you open it. Work down the list and tick off what you have. Nothing here is saved or sent anywhere.
Self Assessment checklist for sole traders
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Register first
If you have never filed a return, you tell HMRC you need to by registering for Self Assessment by 5 October after the tax year ends. After that date HMRC sends a letter with a deadline, but the payment date does not move.
The dates that matter
An online return and the tax owed are both due by 31 January. File by 30 December if you want what you owe collected through your tax code. A paper return has to reach HMRC by 31 October. Late filing or late payment can lead to penalties.
Afterwards matters most
The people who dread January are the ones who spent the money. Putting a share of each payment aside as it arrives takes the surprise out of the bill.
Figures for the 2026/27 tax year, checked 25 October 2026. Sources: Self Assessment tax returns deadlines. An estimate, not advice. SideTill is not tax software.
Keep the number for every month
SideTill is the simple record of your side hustle: log the job, send the invoice, record the money when it comes in, and see whether the month actually made you money. It also shows your best month, so you can tell a bad month from a bad habit.
Get SideTill
No account. No sign-up. Your data stays on your phone. The basics are free to use.
Questions
Do I have to keep receipts?
Keep records of everything you claim. A photo of the receipt kept with the cost is enough for most people.
Is this tax advice?
No. It is a list of the steps and dates from gov.uk. For your own numbers use your return, or ask HMRC or an accountant.
What is a payment on account?
An advance towards next year's bill, in two halves on 31 January and 31 July. See the payments on account page for the sums.