Do I Need to Do a Self Assessment If I Earn Under 12k?

Tax Queen

Tax Expert @ Pie

4 min read

Do You Need to File a Self Assessment on a Low Income?

Often, yes. If you earn more than £1,000 from self-employment or property in a tax year, you normally need to register and file a Self Assessment return, even if your total income is under the £12,570 personal allowance.

Earning under £12k usually means you will not owe any Income Tax. But filing a return and paying tax are two different things, and HMRC still needs to see your figures to confirm nothing is due.

The Thresholds That Cause Confusion

The personal allowance is the amount you can earn each year before paying Income Tax. For 2026/27 it is £12,570, and it decides how much tax you pay, not whether you need to file.

The trading allowance is a separate £1,000 tax-free amount for self-employed income. If your gross income (everything you earn before taking off expenses) is £1,000 or less, you usually do not need to tell HMRC at all.

Landlords get a matching £1,000 property allowance for rental income. If your gross income goes over £1,000, you can choose to deduct the allowance instead of your actual expenses, whichever gives you the lower bill.

You may see other figures mentioned online. For side income, the £1,000 gross figure is the one to keep an eye on.

When You Might Need to File Anyway

Your gross self-employment income is over £1,000 in the tax year.
Your gross rental income is over £1,000 in the tax year.
HMRC has sent you a notice to file a return, even if you think you owe nothing.
You want to pay voluntary Class 2 National Insurance to protect your State Pension record when your profits are low.
You have sold assets at a gain above the £3,000 Capital Gains Tax annual exempt amount, in which case you may need to report it.

Key Dates for Your Return

You must register by 5 October after the end of the tax year you started self-employment or letting. If you started during 2025/26, that means registering by 5 October 2026.

Paper returns for 2025/26 were due by 31 October 2026, and the online return and any tax owed are due by 31 January 2027. If you have not signed up yet, our guide on how to register for Self Assessment with a Government Gateway login walks you through it step by step.

Missing the deadline brings a £100 penalty straight away, with more charges after 3 months. The good news is that payments on account (advance payments towards next year's bill) are not needed if your bill is under £1,000, which covers most low earners.

Does Making Tax Digital Affect You?

Making Tax Digital (MTD) means keeping digital records and sending quarterly updates to HMRC using recognised software. Since 6 April 2026 it has applied to sole traders and landlords whose qualifying income (gross self-employment plus property income, before expenses) was over £50,000 in 2024/25.

The threshold falls to £30,000 from 6 April 2027 and £20,000 from 6 April 2028. If your income is under £12k, you are not required to join under the current thresholds, though it is worth reading any letter HMRC sends. Our guide to Making Tax Digital for sole traders and landlords explains more.

Common Worries and Mistakes

In online communities, the same concerns come up again and again. Most of them stem from mixing up the different allowances.

Assuming low income means no return. Being under the personal allowance does not cancel the need to file.
Using profit instead of gross income. The £1,000 test is based on what you earn before expenses, not what is left afterwards.
Thinking a PAYE job covers everything. Your employer only taxes your wages, so side income still needs reporting.
Ignoring a notice to file. People are often surprised to get a £100 penalty even though they owed no tax.
Worrying about past years. If you should have registered earlier, coming forward to HMRC sooner is usually far less stressful than waiting.

If you feel unsure where to start, our article on how to get help with Self Assessment covers your options in plain English.

Make It Simple with Pie Tax

Pie Tax tracks your income and expenses, sorts your expenses automatically and shows you a real-time tax estimate, so you always know where you stand. It also sends MTD quarterly updates and Self Assessment returns straight to HMRC.

Whether you earn a little or a lot, you can file with confidence and avoid surprise penalties. Try Pie Tax for free and get your return sorted well before the deadline.