What is a tax return?
A tax return is the annual form, usually the SA100 for individuals, on which you report income and gains to HMRC so it can work out the tax you owe.
What a tax return means
For individuals, the main form is the SA100, with supplementary pages for particular types of income, such as SA102 for employment, SA103 for self-employment, SA105 for property and SA108 for capital gains. Partnerships file an SA800 and companies file a Company Tax Return, the CT600. Almost all returns are now filed online.
The return covers a tax year from 6 April to 5 April. Online returns are due by 31 January after the tax year ends, and paper returns by 31 October.
Example
A graphic designer has a salary and a small freelance business. Her return includes the SA100, an SA102 for her job and a short SA103 for the business, which made a profit of £14,000. Tax on her salary has already been deducted through PAYE, so the return calculates the extra income tax and Class 4 National Insurance due on the freelance profit.
What goes on the return
- income from employment, self-employment and partnerships
- rental income and expenses
- dividends and savings interest
- capital gains
- pension contributions and Gift Aid donations, which can increase your tax relief
- the High Income Child Benefit Charge, where it applies
You need your UTR number, P60 and P11D if employed, records of business income and expenses, bank interest and dividend statements, and details of any assets sold. Keep supporting records for at least 22 months after the end of the tax year, or five years after the filing deadline if you are self-employed.
If you no longer need to file, for example because you stopped trading, tell HMRC so it cancels the notice to file.
Why it matters
An accurate return means paying the right tax and avoiding penalties. You can amend a return within 12 months of the 31 January deadline. Our guide on how to pay your Self Assessment tax bill covers deadlines, payment methods and payment plans.
Common questions
Yes. A company files a Company Tax Return (CT600) with HMRC within 12 months of the end of its accounting period, along with its accounts and tax computation. Its directors may also need personal Self Assessment returns for their own income.
Yes. You can amend an online return within 12 months of the 31 January filing deadline, usually through the same account you filed it from. After that, you would need to write to HMRC to claim overpaid tax, within four years of the end of the tax year.