Self Assessment Tax Calendar 2025/26: Key Dates You Need to Know
Key Dates to Stay Ahead for 2025/26
Stay on top of your tax responsibilities for the 2025/26 tax year with this complete guide from SBX Accountants. Whether you're a sole trader, partner, or limited company director, these Self Assessment dates will help you avoid penalties and plan ahead.
Key Tax Year Transition Dates
30 April 2025 – Final Deadline for Late 2023/24 Returns
Missed the January deadline? File now to avoid daily penalties of £10 starting 1 May.
31 July 2025 – Second Payment on Account (2024/25)
Due if you make payments on account. This helps spread your tax liability across the year.
5 October 2025 – Register for Self Assessment
If you became self-employed or received untaxed income in 2024/25, register with HMRC by this date.
31 October 2025 – Paper Return Deadline
If filing a paper tax return, this is your final date. We recommend filing online for extended deadlines and faster processing.
30 December 2025 – Collect Tax via PAYE Option
File your online return by this date if you owe less than £3,000 and want the tax collected via your tax code.
31 January 2026 – Final Deadline
The most important date of the year. You must:
- File your 2024/25 Self Assessment return
- Pay any tax due
- Make your first 2025/26 payment on account (if applicable)
31 July 2026 – Second 2025/26 Payment on Account
Another advance tax payment due, based on your previous year’s tax bill. If income has fallen, you may be able to reduce it.
What’s New for 2025/26?
Making Tax Digital (MTD) for Income Tax
Starting 6 April 2026, MTD applies to those earning over £50,000 from self-employment or property income. Digital records and quarterly updates will be mandatory. The £30,000+ threshold follows in 2027.
Personal Allowance Still Frozen
The personal allowance remains at £12,570, meaning more people may be pushed into higher tax bands due to inflation. Review your tax position early.
Let SBX Accountants Help You Stay Ahead
At SBX Accountants, we support sole traders, landlords, and company directors through the full Self Assessment cycle. We’ll:
- Handle all tax return filing
- Help you reduce payments on account if appropriate
- Keep you informed of MTD changes
- Ensure no deadline is ever missed
Need help navigating your Self Assessment deadlines? Request a callback or speak to our team today.
