How to Register as Self-Employed in the UK: Complete 2026 Guide

By Ben, Founder of Solofold  ·  Published May 2026  ·  6 min read

I registered as self-employed over 20 years ago. It was simpler than I expected — and the penalties for not registering on time are very real. This guide covers everything you need to know.

Do you actually need to register?

You must register as self-employed with HMRC if you earn more than £1,000 from self-employment in a tax year. This is called the "trading allowance." Below £1,000, you don't need to register or pay tax on that income.

Above £1,000, registration is not optional. HMRC needs to know you're trading so they can collect Income Tax and National Insurance. The good news: registering is straightforward and takes about 20 minutes online.

The deadline — don't miss this

You must register by 5 October following the end of the tax year in which you started self-employment.

Example: If you started freelancing in June 2025 (tax year 2025/26), you must register by 5 October 2026.

Missing this deadline triggers automatic penalties. HMRC charges a percentage of the tax owed as a late registration penalty — the longer you delay, the higher it gets. Register early. There is no disadvantage to registering before the deadline.

How to register — step by step

Step 1: Create a Government Gateway account
Go to: gov.uk/register-for-self-assessment
Click "Register if you're self-employed." You will need to create a Government Gateway account if you don't have one. Use your personal email address. Write down your Government Gateway user ID — you'll need it every year.

Step 2: Complete the SA1 or CWF1 form
HMRC will guide you through either the SA1 (Self Assessment registration) or CWF1 (for self-employment specifically). Fill in your personal details, start date of self-employment, and the type of work you do. It takes about 15-20 minutes.

Step 3: Receive your UTR number
HMRC will send your Unique Taxpayer Reference (UTR) by post within 10 working days. This 10-digit number is your permanent tax identity as a self-employed person. Keep it safe. You will use it every year on your tax return.

Step 4: Activate your Self Assessment account
Once you receive your UTR, return to the Government Gateway and activate your Self Assessment account. HMRC sends an activation code by post (separate from the UTR letter). This completes your registration.

National Insurance — what you owe

As a self-employed person, you pay two types of National Insurance:

Class 2 NI: A flat rate of £3.45/week if your profits exceed £6,725/year. Paid via your Self Assessment return — not separately.

Class 4 NI: 9% on profits between £12,570 and £50,270. 2% on profits above £50,270. Also paid via Self Assessment.

What happens after you register

File a tax return every year. Once registered, HMRC expects a Self Assessment return by 31 January every year — even if you earned very little. Missing this triggers automatic £100 penalties.

Keep records for 5 years. You must keep all income and expense records for 5 years after the filing deadline. HMRC can investigate any of those years.

Pay tax twice a year — potentially. If your tax bill exceeds £1,000, HMRC will require Payments on Account. These are advance payments — see our Payments on Account guide for full details.

Start tracking income and expenses now. From your first day of self-employment, keep records of every payment in and every business cost out. Organised from day one means a stress-free January.

Common mistakes to avoid

Registering late. HMRC penalties for late registration compound over time. Register as soon as you start earning above £1,000 — don't wait until January.

Not setting aside tax as you go. Income tax is not deducted at source for self-employed people. Set aside 25-30% of every payment into a separate account from day one.

Losing your UTR number. Write it down and store it safely. You need it every year for your tax return. You can recover it from HMRC but it takes time.

Not keeping records. "I'll sort it out in January" is the most expensive thing a sole trader can say. Start tracking from day one.