Self-Employment Tax: Register to Submit / Lesson 3 of 12
Registering with HMRC and getting your UTR
Register late and the penalty can arrive before your first tax bill does.
The short answer
- ✓ Registering gives you a UTR, and you cannot file without one
- ✓ Allow a few weeks: the UTR and the activation code arrive separately by post
- ✓ Give your genuine start date, because it sets which tax year you must declare
- ✓ Once registered, HMRC expects a return every year until you deregister
What registering actually gives you
Registering for Self Assessment produces one thing you cannot file without: a Unique Taxpayer Reference, or UTR. It is a ten-digit number, it belongs to you rather than to your business, and you keep it for life even if you stop trading and start again years later.
The sequence, and why timing matters
1. Register online with HMRC
2. UTR arrives by post around 10 working days
3. Activation code arrives by post a further few days
4. Sign in and file only now is this possibleTwo separate letters, each posted, each taking days. That is why "I will register in January" fails: the January deadline is for filing, and you may physically not be able to file in time if you start the process then.
What you will be asked for
- Your National Insurance number
- The date you started trading
- What your business does, in plain terms
- Your contact details and address
You do not need a business name, a business bank account, or any accounts prepared. Sole traders trade under their own name unless they choose otherwise.
The bit HMRC does not spell out
The start date you give is not a formality. It sets which tax year your first return covers, and it can pull an earlier year into scope. If you did paid work in February but put your start date as April because that felt tidier, your first return is now for the wrong year, and the February income sits in a year you have not declared.
Give the date you genuinely first traded, even if it is awkward, even if it was months ago. Correcting a start date later is straightforward. Explaining undeclared income is not.
Keeping the number safe
Your UTR is the key to your tax record and it is a common target for fraud. HMRC will never ring you to ask for it, and never texts asking you to confirm it. Store it somewhere you can find it in five years, because you will need it every January.
Common mistakes
- Leaving registration until the filing deadline. The post alone can take a fortnight.
- Giving a tidy start date rather than the real one. It changes which year you are declaring.
- Registering when you did not need to. Once registered, HMRC expects a return every year until you tell it you have stopped.
- Assuming registering as self-employed covers a company. A limited company is a completely separate registration and a different tax regime.
Key takeaways
- ✓ Registering gives you a UTR, and you cannot file without one
- ✓ Allow a few weeks: the UTR and the activation code arrive separately by post
- ✓ Give your genuine start date, because it sets which tax year you must declare
- ✓ Once registered, HMRC expects a return every year until you deregister
Check you have got it
3 quick questions. No score is kept, and you can change your mind.
1. What is a UTR?
2. Why is registering in January a problem, even though the filing deadline is 31 January?
3. You did your first paid work in February but tell HMRC you started in April. What is the risk?
Sources
Finished this lesson?
Mark it done and we will remember where you got to.
You are 3 lessons in. Want to keep your progress?
Right now your place is saved in this browser only. A free account keeps it across devices, unlocks the end-of-course exam and certificate, and gives you a personal action plan at the end. No card, no upsell.
