Self Assessment Tax Return
Self Assessment is how HMRC collects Income Tax and National Insurance from self-employed people, company directors and anyone with income that is not taxed at source. It sounds complicated but once you understand the process and have good records, it is very manageable. This pathway takes you through everything you need to complete your return accurately and on time.
Self Assessment is an annual tax return you submit to HMRC covering the previous tax year (6 April to 5 April). You report all your income — from self-employment, employment, property, investments and any other source — and HMRC calculates how much tax you owe.
You need to register for Self Assessment if you are self-employed and earning more than £1,000 per year, a company director, earning more than £100,000 per year, have income from property, or have other untaxed income above certain thresholds.
The key deadlines are: 31 October for paper returns, 31 January for online returns (covering the tax year that ended the previous April), and 31 January for paying any tax owed. Miss these deadlines and you face automatic penalties — £100 for being one day late, rising significantly the longer you leave it.
The tax year runs from 6 April to 5 April. So your 2024–25 tax return covers income earned between 6 April 2024 and 5 April 2025. The deadline to file this online is 31 January 2026.
Good to know
- Register for Self Assessment as soon as you start self-employment — do not wait for the deadline
- File online rather than on paper — you get an extra three months and it is much easier
- Set a reminder for 31 January every year — it is easy to forget until it is too late
Watch out for
- Missing the registration deadline of 5 October in your second year of trading
- Assuming that because you have not received a letter from HMRC, you do not need to file
- Leaving it until January and then rushing — errors made under pressure are common
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