When you need to register

You must register for Self Assessment by 5 October following the end of the tax year (6 April–5 April) in which you started trading or earning untaxed income. Miss it and HMRC can charge a failure-to-notify penalty.

How to register

Register online through the HMRC website. You’ll get a Unique Taxpayer Reference (UTR) and a Government Gateway account. Keep both safe — you’ll need them every year.

What you’ll need afterwards

Keep records of all business income and expenses from day one, set aside money for tax (a good rule of thumb is 20–30% of profit), and diarise the 31 January filing deadline. An accountant can register you and handle the whole cycle for you.

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