Answers · UK 2025/26

Do I need to register for Self Assessment in the UK?

You must register for Self Assessment if you are self-employed with income over £1,000, a company director without all your income taxed at source, receive rental or investment income above the relevant allowances, or your income exceeds £150,000 while employed. Registration deadline is 5 October following the end of the tax year in which you first need to file.

Last updated: 2 July 2026Last reviewed: 2 July 2026How we verify

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Self Assessment registration is required whenever HMRC does not already have enough information to tax your full income correctly through other routes like PAYE, and missing the deadline can trigger automatic penalties even before any tax is actually owed. **Common triggers for registration** You generally need to register if: you are self-employed or a partner in a business partnership with income over the £1,000 trading allowance; you are a company director (unless all your income is already taxed at source with nothing further due); you have rental income above the £1,000 property income allowance; you have significant savings, investment or dividend income above the relevant tax-free allowances; you need to claim certain reliefs like higher-rate Gift Aid relief; you or your partner earn over £60,000 and receive Child Benefit (High Income Child Benefit Charge); or your total employed income exceeds £150,000. **The registration deadline** You must register by 5 October following the end of the tax year in which you first became liable -- for example, if you started self-employment in June 2026 (within the 2026/27 tax year, running 6 April 2026 to 5 April 2027), you must register by 5 October 2027. **Filing and payment deadlines** Once registered, the online filing deadline is 31 January following the tax year end, which is also the deadline for paying any tax owed -- paper returns have an earlier deadline of 31 October. **Penalties for missing registration** Missing the registration deadline itself does not automatically trigger a penalty, but if this causes you to also miss the subsequent filing or payment deadlines, penalties apply: an immediate £100 penalty for late filing (even if no tax is owed), rising further after 3, 6 and 12 months of continued lateness, plus separate interest and penalties for late payment. **How to register** Registration is done online via gov.uk, and you will need a Unique Taxpayer Reference (UTR) issued after registering, which can take up to 10 working days (longer if by post) -- register with enough time before the deadline to allow for this processing. **If you're unsure whether you need to register** Use HMRC's online checking tool, or consider your specific income sources against the triggers above -- when in doubt, it is generally safer to register (you can always confirm no tax is due) than to risk missing a genuine obligation and facing penalties. **Practical tip** If you have started any new income source this tax year that might trigger a Self Assessment obligation -- a side business, rental property, or significant investment income -- mark the 5 October deadline in your calendar now rather than waiting until closer to the date, since gathering the necessary information can take longer than expected.