Guide · 4 minute read · Updated 10 Jul 2026

Do I need to file a Self Assessment tax return?

Most employees taxed through PAYE never need to file. You have to send a return when you have income HMRC does not already tax at source, or when a specific rule pulls you in, and the list of those rules is shorter than people fear.

Most employees never need to file

If your only income is a salary or a pension, tax is collected automatically through PAYE and your tax code, and there is nothing to file. HMRC does not want a return from everyone. The system exists to catch income it cannot see: self-employment, rent, large savings or dividend income, capital gains, and a handful of charges that only a return can settle.

So the real question is not "should I file to be safe" but "does one of the specific triggers apply to me". If none does, filing anyway just creates a return you then have to keep filing until you tell HMRC to stop.

The triggers that force a return

You must send a Self Assessment return for 2026/27 if any of these apply:

• You were self-employed as a sole trader and your gross trading income was more than £1,000.
• You were a partner in a business partnership.
• Your total taxable income was over £150,000 (the threshold for people taxed only through PAYE).
• You or your partner had income over £60,000 and one of you claimed Child Benefit, so the High Income Child Benefit Charge applies. From 2025/26 employees can instead pay this charge through their tax code, which avoids a return.
• You had untaxed income HMRC does not already know about: rental income, tips, commission, foreign income, or savings and dividend income above your allowances.
• You had Capital Gains Tax to pay, for example on selling a second property, shares outside an ISA, or crypto.

If you are unsure, GOV.UK has a short checker, and our self-employed tax calculator shows what a sole trader would actually owe once income tax and National Insurance are added up.

The £1,000 trading and property allowances

Two allowances keep small amounts of side income out of the system entirely. The £1,000 trading allowance means you can earn up to £1,000 from self-employment, a side hustle or selling online before you need to register or file. A separate £1,000 property allowance does the same for rental income.

These are gross figures, measured before expenses. Earn £1,001 from a side gig and you cross the line, even if your profit after costs is tiny. Below £1,000, you have nothing to declare. Above it, you either claim the allowance instead of your actual expenses or deduct real costs, whichever leaves you better off.

Deadlines and what happens if you miss them

If you need to file for the first time, register by 5 October after the tax year ends. Then there are two filing deadlines: 31 October for a paper return, and 31 January for an online one. The tax you owe is also due by 31 January.

Miss the online deadline and you get an automatic £100 penalty, even if you owe no tax and even if you file one day late. After three months, daily penalties of £10 a day start, up to £900. At six and twelve months, further charges of 5% of the tax due (or £300 if greater) are added, and interest runs on anything paid late. The £100 is easy to avoid; the later penalties are the ones that turn a forgotten return into real money.

Common questions

Do I need to file a tax return if I earn under £1,000 from a side hustle?

No. The £1,000 trading allowance means gross self-employed or side income up to £1,000 a year does not need to be declared or registered. Cross £1,000 in gross income and you must register for Self Assessment, even if your profit after costs is small.

I'm employed and pay tax through PAYE. Do I still need to file?

Usually not. If your only income is a salary taxed through PAYE, there is nothing to file. You are pulled in only by a specific trigger, such as income over £150,000, untaxed rental or investment income, capital gains, or the High Income Child Benefit Charge.

What are the Self Assessment deadlines for 2026/27?

Register by 5 October after the tax year ends. Paper returns are due 31 October, online returns by 31 January, and any tax owed is also due 31 January. Missing the online deadline triggers an automatic £100 penalty even if no tax is due.

What is the penalty for filing my tax return late?

An automatic £100 for missing the 31 January online deadline, however little you owe. After three months, daily penalties of £10 (up to £900) start; at six and twelve months a further 5% of the tax due (or £300 if greater) is added, plus interest on late payment.

Guidance and education, not regulated financial advice.