Self Assessment Deadlines
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Statutory dates for the 2025/26 Self Assessment cycle, with the next live milestone foregrounded.
Register for Self Assessment by 5 October 2026Next milestone
2025/26 cycle timeline
Register
5 Oct 2026
133 days
Paper return
31 Oct 2026
159 days
Online return + balancing payment
31 Jan 2027
251 days
Second payment on account
31 Jul 2027
432 days
Estimate the tax bill before you file
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Late filing penalties
1 day late
£100 fixed penalty, applies even if no tax is due.
3 months late
£10 per day for up to 90 days (maximum £900), in addition to the fixed penalty.
6 months late
A further 5 percent of the tax due, or £300 if greater.
12 months late
Another 5 percent of the tax due, or £300 if greater. Deliberate withholding can attract higher percentages.
Who needs to file Self Assessment?
- Self-employed with gross trading income above £1,000
- Income from property above £1,000 gross
- Company directors with untaxed income
- Dividend income above the dividend allowance
- Capital gains above the Annual Exempt Amount
- Total income above £100,000
- Liable to the High Income Child Benefit Charge
- Untaxed income, tips, commission, foreign income
- Partners in a business partnership, trustees
Frequently asked questions
When is the Self Assessment deadline for 2025/26?
The online filing and payment deadline for 2025/26 is 31 January 2027. The paper-return deadline is 31 October 2026. If you have not previously filed, you must register with HMRC by 5 October 2026.
What happens if I miss the Self Assessment deadline?
HMRC charges a £100 fixed penalty as soon as a return is one day late. After 3 months, daily penalties of £10 apply for up to 90 days (capped at £900). After 6 months and 12 months, a further 5 percent of the tax due (or £300 if greater) is added at each milestone. Interest also runs on unpaid tax from the day after the payment due date.
Can I get an extension on my Self Assessment?
HMRC does not grant extensions in advance. You can appeal late-filing penalties after the event if you have a reasonable excuse, for example serious illness, bereavement, software failure, or HMRC service outage. File the return as soon as the obstacle is removed.
Do I need to file a Self Assessment return?
Filing is generally required if you were self-employed with gross trading income above £1,000, had untaxed property income above £1,000, are a company director (in many cases), received dividends above your allowances, made capital gains above the annual exempt amount, earned over £100,000, or were liable to the High Income Child Benefit Charge.
When can I file my 2025/26 Self Assessment?
HMRC opens online filing for 2025/26 from 6 April 2026. You can submit any time between then and the 31 January deadline that follows.