Answers · UK 2025/26
When do I need to register for Self Assessment?
You must register for Self Assessment if you are self-employed with income above the £1,000 Trading Allowance, or if you received untaxed income above £2,500, earn above £100,000, have capital gains above the £3,000 Annual Exempt Amount, or meet several other specific triggers. The registration deadline is 5 October after the tax year ends.
Full answer
HMRC requires you to register for Self Assessment if any of the following apply for the tax year: **Common triggers:** 1. **Self-employment:** Profits above the £1,000 Trading Allowance (even for side businesses or gig work). 2. **High income:** Adjusted net income above £100,000 (Personal Allowance begins to taper). 3. **High Income Child Benefit Charge (HICBC):** Either partner's income exceeds £60,000 and the household receives Child Benefit. 4. **Untaxed income above £2,500:** e.g. rental income (gross receipts above £10,000 also trigger SA), overseas income, trust income, foreign income. 5. **Capital gains:** Gains exceed the £3,000 Annual Exempt Amount (AEA for individuals in 2026/27). 6. **Dividends:** Taxable dividends (above £500 allowance) if you do not have sufficient PAYE tax to cover them or they push you above basic rate. 7. **Director of a company:** Most company directors must complete a return. 8. **Foreign income:** Any untaxed foreign income (employment, rental, pensions, investments). 9. **Minister of religion** or other specific occupations. 10. **Voluntary registration:** Self-employed people earning below £1,000 may register voluntarily to build NI credits or to declare losses. **Deadlines:** - **Registration deadline:** 5 October following the end of the tax year (so 5 October 2026 for 2025/26 returns). - **Paper return:** 31 October 2026. - **Online return:** 31 January 2027. - **Tax payment:** 31 January 2027 (first payment on account also due for new SA filers). **Penalties for late registration:** HMRC can charge a penalty if you fail to notify them of a liability to tax by the 5 October deadline — typically £100 for the first 3 months late, rising substantially beyond that. Prompt registration avoids interest on unpaid tax and late filing penalties.
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This answer is informational only and does not constitute financial, tax or legal advice. Figures are for the 2025/26 UK tax year. See our methodology and sources.