Business Handbook
All Pathways
Legal & Registration

Registering With HMRC

1 hour·8 steps·Free

Registering with HMRC is one of the first things you need to do when you start a business. Get it right from the start and you will avoid penalties, know exactly what taxes you owe, and have a clear picture of your obligations. This pathway covers everything you need to register correctly — whether you are a sole trader, a limited company, or an employer.

Please note: This guide is for general information only. It is not legal or financial advice. Always check current regulations and seek professional guidance where needed.

If you are a sole trader, you need to register with HMRC for Self Assessment. This is how you report your income and pay Income Tax and National Insurance each year. You must register by 5 October in the second tax year of trading — so if you started trading in the 2024–25 tax year, you must register by 5 October 2025.

Register online at gov.uk/register-for-self-assessment. You will need your National Insurance number and contact details. HMRC will send you a Unique Taxpayer Reference (UTR) number by post within 10 working days. Keep this safe — you will need it every time you deal with HMRC.

Once registered, you will need to file a Self Assessment tax return each year by 31 January (online) covering the previous tax year (6 April to 5 April). You pay any tax owed at the same time. The first payment can feel large because HMRC also asks for a "payment on account" — an advance payment towards next year's bill.

If you are already employed and also running a business on the side, you still need to register for Self Assessment to declare your self-employment income. Your employer will continue to deduct tax from your salary through PAYE.

Good to know

  • Register as soon as you start trading — do not wait until the deadline
  • Keep a record of all income and expenses from your first day of trading
  • Set aside 25–30% of your profit for tax as you go

Watch out for

  • Missing the 5 October registration deadline — HMRC can charge penalties
  • Assuming that because you earn below the Personal Allowance you do not need to register — you still do if you are self-employed
  • Not keeping records — HMRC can ask to see them for up to five years

Ready for the next step?

Browse all pathways or explore our handbooks and templates for deeper guidance.

All PathwaysExplore Handbooks