Do you need to register?

If you have started working for yourself and earned more than £1,000 in self-employment income in a tax year, you need to register for Self Assessment. You can also use HMRC’s online checker if you are not sure. The deadline to register is 5 October following the end of the tax year in which you started trading, so if you started trading during the 2025 to 2026 tax year, you would need to register by 5 October 2026.

What information you will need

How to register, step by step

Follow these steps in order, using the official HMRC links below to complete each one.

  1. Check if you need to register. Use HMRC’s online checker to confirm you need to send a Self Assessment return before you start.
  2. Gather your details. Have your National Insurance number, contact details, date of birth, and your business start date and description to hand.
  3. Register with HMRC. Go to gov.uk/register-for-self-assessment and select ‘Start now’ to complete HMRC’s online registration form. If you do not already have a Government Gateway account, you can create one as part of this process.
  4. Wait for your Unique Taxpayer Reference (UTR). HMRC posts your ten-digit UTR, usually within around ten working days (longer if you are abroad). You can check how long HMRC is taking to reply if it seems delayed.
  5. Activate your online account. A separate activation code arrives by post soon after your UTR; you will usually need to enter this within 28 days to fully activate your Self Assessment online account.
  6. File your return each year. Once activated, sign in at gov.uk/log-in-file-self-assessment-tax-return using your UTR and Government Gateway details to complete and submit your return.
  7. Pay any tax you owe. The filing and payment deadline is 31 January following the end of the tax year. You can pay online via gov.uk/pay-self-assessment-tax-bill.

Your Unique Taxpayer Reference (UTR)

Once registered, HMRC will post you a ten-digit Unique Taxpayer Reference, usually within around ten working days. If it is taking longer, you can check HMRC’s current response times, or find a lost UTR if you have registered before. You will need this UTR every time you file a Self Assessment return, so it is worth registering in good time rather than leaving it until close to a filing deadline.

What happens after you register

Each year you will need to complete a Self Assessment return declaring your income, and pay any Income Tax and National Insurance due. The main filing and payment deadline is 31 January following the end of the tax year, for returns filed online. You can check the full list of Self Assessment deadlines on gov.uk.

New to self-employment? Talk to us, we can register you for Self Assessment and take the paperwork off your hands from day one.

How MLA Chartered Accountants can help

We can register you for Self Assessment, or take the whole process off your hands entirely, then prepare and file your return each year so you know exactly what you owe and when it is due.