How to Register for Self Assessment: A Guide for the Self-Employed
What Is Self Assessment?
Self Assessment is the system HMRC uses to collect Income Tax that is not deducted automatically through PAYE. If you work for yourself or receive income that has not been taxed at source, it is your responsibility to tell HMRC and file a tax return. The first step is registering — and missing the deadline can lead to penalties.
Who needs to register?
You generally need to register for Self Assessment if, in the previous tax year (6 April to 5 April), any of the following applied:
You were self-employed as a sole trader and earned more than £1,000 (the trading allowance) before expenses
You received rental income from property
You were a partner in a business partnership
You had untaxed income from dividends, savings, investments or a side hustle
You were liable for the High Income Child Benefit Charge
The key deadline: 5 October
The most overlooked date is 5 October. You must tell HMRC that you need to file a return by 5 October following the end of the tax year in which you started earning the untaxed income.
For example, if you became self-employed during the 2024/25 tax year, your registration deadline is 5 October 2025.
How to register
Registration is done online through your Government Gateway account on the HMRC website.
Self-employed: register as a sole trader — this also sets up your Class 2 and Class 4 National Insurance
Other untaxed income: complete form SA1
Partnerships: the partnership and each partner register separately
You will need your National Insurance number and personal details. HMRC then issues your Unique Taxpayer Reference (UTR), usually within around 10 working days (longer if you are abroad).
What happens after you register
Once registered, you must file a return and pay any tax due for each relevant year:
Paper return: by 31 October
Online return: by 31 January
Payment: any tax owed is due by 31 January, with a possible payment on account by 31 July
You only register once. In following years HMRC will expect a return until you tell them your circumstances have changed.
A change on the horizon
The government has announced plans to raise the Self Assessment reporting threshold for trading income from £1,000 to £3,000. This is not yet in force — it is expected within the current parliament — so for now the £1,000 threshold still applies.
FAQ:
Do I need to register if I earn less than £1,000?
No. Income within the £1,000 trading allowance does not need to be reported, though it is wise to keep records.
How long does it take to get a UTR?
Usually around 10 working days, or up to 21 days if you are abroad.
What happens if I miss the 5 October deadline?
Register as soon as you can. If you pay all the tax owed by 31 January, the failure-to-notify penalty may be reduced to nil.
Do I need to register every year?
No, you register once. HMRC will expect a return each year until you tell them your circumstances have changed.
