Filing Self Assessment: deadlines, penalties and how to submit
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In short. HMRC require a Self Assessment return where someone is self-employed and earned over £1,000 in trading income, is a partner in a partnership, has untaxed income over £2,500, has rental income over £2,500 (or gross rents over £10,000), has total income over £150,000, has Capital Gains above the annual exempt amount, has to pay the High Income Child Benefit Charge, or has been told by HMRC to file. The HMRC online checker at gov.uk/check-if-you-need-tax-return is definitive.
Self Assessment is HMRC's process for collecting tax on income that is not taxed through PAYE. Most employees never need to file. The triggers below cover the most common situations published in HMRC's own guidance.
Quick answer: Do I need to file Self Assessment? →
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Common triggers for a Self Assessment return
- Self-employed sole trader with gross trading income over £1,000 (the trading allowance)
- Partner in a business partnership
- Director of a limited company with untaxed income (HMRC require many directors to file, though there is no statutory rule by job title alone)
- Untaxed income over £2,500 — for example, freelance work, tips, commission
- Rental income over £2,500 net (or gross rents over £10,000)
- Total taxable income over £150,000 in 2025/26 (raised from £100,000)
- Capital Gains above the £3,000 Annual Exempt Amount for 2025/26, or disposals over four times the AEA
- Liable for the High Income Child Benefit Charge (adjusted net income £60,000+ and the household claims Child Benefit)
- Foreign income, or non-UK domicile reporting
- State Pension is the only income but exceeds the Personal Allowance
Side-hustles and the £1,000 trading allowance
The trading allowance lets a person earn up to £1,000 of gross trading or miscellaneous income in a tax year without telling HMRC. Above £1,000 a Self Assessment return is required even where the actual profit is small. The allowance applies separately to trading and property income.
Online marketplace and gig-platform income (eBay, Vinted, Etsy, Airbnb, Uber, Deliveroo, etc.) counts as trading income for this test. From January 2024, UK digital platforms report seller activity to HMRC under OECD rules where sellers have 30+ sales a year or earn over roughly €2,000 (about £1,700).
How to register
Anyone who needs to file for the first time must register with HMRC by 5 October following the end of the tax year — so 5 October 2026 for 2025/26 income. Registration is at gov.uk/register-for-self-assessment. HMRC then issue a Unique Taxpayer Reference (UTR), which arrives by post within about 10 working days.
FAQ
- I'm employed but have a small freelance income — do I need to file?
- Yes if the gross freelance income is over £1,000 in the tax year. Below £1,000 the trading allowance covers it and no return is needed unless HMRC asks for one.
- Do PAYE employees ever have to file?
- Sometimes — common reasons are total income over £150,000, untaxed savings/dividend income over the relevant allowance, capital gains above the AEA, or the High Income Child Benefit Charge.
- What if HMRC sent me a notice to file but I don't think I should have to?
- Once HMRC issue a notice the return is legally due, even if no tax is owed. The remedy is to file and then ask HMRC to withdraw the notice using their online service or by writing.