When do I need to register for Self Assessment?

Full answer

If you become newly self-employed, start receiving rental income, become a company director, or otherwise need to file a Self Assessment tax return for the first time, you must register with HMRC by 5 October following the end of the tax year in which the requirement to file first arose. For income or activity that begins during the 2026/27 tax year (6 April 2026 to 5 April 2027), the registration deadline is 5 October 2027, even though the actual tax return itself is not due until 31 January 2028. This gap exists because registering triggers HMRC to issue you a Unique Taxpayer Reference (UTR) and, for self-employed individuals, a National Insurance registration for Class 2/4 purposes, and this process can take several weeks, particularly if you register close to the deadline. Missing the 5 October registration deadline can result in a "failure to notify" penalty, calculated as a percentage of any tax that was paid late as a result, separate from the late filing and late payment penalties that apply if the return itself is late. It is worth registering as soon as you know you need to -- there is no penalty for registering early, and doing so gives you more time to set up your online HMRC account and gather the records you need well before the January filing deadline arrives.

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