# Self Assessment for sole traders, topic by topic

Canonical: https://taxmo.co.uk/self-assessment-guide

If you work for yourself in the UK you report your profit to HMRC through a Self Assessment tax return. The tax year runs from 6 April to 5 April. Each page below covers one part of it, with the GOV.UK page it comes from.

## Self Assessment topics

- [SA103S or SA103F](https://taxmo.co.uk/self-assessment-guide/sa103s-or-sa103f): Which self-employment pages to fill in: the short form or the full form.
- [Allowable expenses](https://taxmo.co.uk/self-assessment-guide/allowable-expenses): Business costs you can deduct to work out your taxable profit.
- [The trading allowance](https://taxmo.co.uk/self-assessment-guide/trading-allowance): A tax exemption for small amounts of trading income, instead of claiming expenses.
- [Payments on account](https://taxmo.co.uk/self-assessment-guide/payments-on-account): Two advance payments towards your next tax bill, each usually half of last year's.
- [Deadlines and penalties](https://taxmo.co.uk/self-assessment-guide/deadlines-and-penalties): When to register, file and pay, and what happens if you are late.
- [Registering for Self Assessment](https://taxmo.co.uk/self-assessment-guide/registering): Who has to register as a sole trader and the deadline for doing it.
- [Records to keep](https://taxmo.co.uk/self-assessment-guide/records-to-keep): What records a sole trader must keep and for how long.
- [Basis period reform: the tax year basis](https://taxmo.co.uk/self-assessment-guide/basis-period-reform): Profits are taxed by tax year, and transition profit is spread to 2027 to 2028.

Taxmo keeps your income and expenses so the figures are ready when you file. Taxmo does not submit Self Assessment returns: you send your return to HMRC yourself.

Figures such as the trading allowance and the VAT registration threshold are on our UK tax rates page, with the GOV.UK source for each.

## Read next

- [UK tax rates and thresholds 2026/27](https://taxmo.co.uk/uk-tax-rates)
- [UK tax deadlines](https://taxmo.co.uk/uk-tax-deadlines)
- [Sole trader expenses guide](https://taxmo.co.uk/sole-trader-expenses-guide)

## Sources

- [GOV.UK, Self Assessment tax returns: deadlines](https://www.gov.uk/self-assessment-tax-returns/deadlines)
- [GOV.UK, Register for Self Assessment](https://www.gov.uk/register-for-self-assessment)

Checked against GOV.UK on 6 November 2026. Rules and figures change, so verify on GOV.UK before you rely on this. General information, not tax advice.