Your First Self Assessment / Lesson 1 of 7
Do you need to file at all?
Someone at work said you have to do a tax return. Are they right?
The short answer
- ✓ PAYE handles your salary but not income it never sees
- ✓ A notice to file creates the obligation regardless of anything else
- ✓ The Child Benefit charge pulls in one partner even when neither feels wealthy
- ✓ Once registered, tell HMRC when you stop, or returns keep being expected
Being employed does not exempt you
PAYE handles the tax on your salary, and for most employees that is the end of it. What PAYE cannot handle is income it never sees. That is what pulls people into Self Assessment.
The situations that require a return
| Situation | Return needed? |
|---|---|
| Self-employed or trading income over the trading allowance | Yes |
| Property income over the property allowance | Yes |
| Untaxed income PAYE cannot collect | Usually |
| You or your partner claim Child Benefit and someone earns over the charge threshold | Yes, for the higher earner |
| Capital gains above the annual exempt amount | Yes |
| HMRC has issued you a notice to file | Yes, regardless of anything else |
| Salary and nothing else | No |
| Savings interest inside your allowance | No |
A notice to file overrides everything
If HMRC has sent you a notice to file, you must file, even if you owe nothing and even if none of the situations above apply. Ignoring it because "I do not need to do one" is how people collect a £100 penalty on a nil return.
If you genuinely should not be in Self Assessment, ask HMRC to withdraw the notice. Until they do, the obligation stands.
The bit HMRC does not spell out
Being in Self Assessment is sticky. Once registered, HMRC expects a return every year until you tell it you have stopped. People file one return for a side project that lasted six months, close the project, hear nothing, and assume the matter is closed. It is not: the following January a return is still expected, and a penalty follows when it does not arrive.
If your circumstances end, tell HMRC and ask to be taken out of Self Assessment. It takes minutes and prevents years of penalties on nil returns.
Common mistakes
- Ignoring a notice to file. It creates the obligation on its own.
- Assuming employment covers everything. PAYE cannot see income it never touched.
- Not deregistering when a side project ends. Returns keep being expected.
- Missing the Child Benefit charge. It catches households who never think of themselves as high earners.
Try it on your own numbers
This is the same calculator as the full tool page, using 2026/27 rates.
Your situation (2026/27)
Tick anything that applies. The verdict updates instantly, no sign-up.
Verdict
Based on what you ticked, HMRC expects a Self Assessment tax return.
Nothing you ticked triggers a return, but check with HMRC if your situation is unusual.
Why
What to do next
- Register for Self Assessment to get your UTR (allow ~10 working days).
- File online by 31 January after the tax year ends.
- Pay any tax owed by the same 31 January deadline.
Guide only, it doesn't cover every edge case (trusts, non-residence, ministers of religion, etc.). HMRC's position is final.
Work out the bill
Key takeaways
- ✓ PAYE handles your salary but not income it never sees
- ✓ A notice to file creates the obligation regardless of anything else
- ✓ The Child Benefit charge pulls in one partner even when neither feels wealthy
- ✓ Once registered, tell HMRC when you stop, or returns keep being expected
Check you have got it
3 quick questions. No score is kept, and you can change your mind.
1. HMRC sent you a notice to file but you owe no tax. What must you do?
2. Your side project ended two years ago and you filed a return at the time. What should you have done?
3. You are employed and have savings interest within your personal savings allowance. Do you need to file?
Sources
Finished this lesson?
Mark it done and we will remember where you got to.
