UK Sole Trader Tax Deadlines 2025–26: The Complete Calendar

Self Assessment Deadlines (2024–25 Tax Return)

31 October 2025: Deadline to file your 2024–25 self-assessment tax return on paper. Very few people still use paper, but if you do, this is the date.

31 January 2026: Deadline to file your 2024–25 self-assessment tax return online. This is the deadline that applies to most sole traders. Miss this and HMRC automatically issues a £100 fixed penalty, regardless of whether any tax is owed.

31 January 2026: Deadline to pay any tax owed for 2024-25, plus your first payment on account for 2025–26. Payments on account are advance payments towards next year's tax bill, calculated as 50% of the previous year's liability.

31 July 2026: Second payment on account for 2025–26. This is the mid-year advance payment. If your income has changed significantly, you can apply to reduce your payments on account, but any under-payment will attract interest.

VAT Return Deadlines

VAT return deadlines depend on your VAT period. Most businesses are on a quarterly cycle. The due date is one calendar month and seven days after the end of each VAT period. For a VAT period ending 31 March 2026, the deadline is 7 May 2026.

Under MTD for VAT, both the return and the payment must be made digitally and on time. A late VAT return or payment generates a late payment penalty calculated as a percentage of the VAT owed, starting at 2% after 15 days, rising to 4% after 30 days.

Annual Accounting Scheme users have different deadlines: the return and final payment are due two months after your annual accounting year ends.

MTD Income Tax Quarterly Deadlines (From April 2026)

For those mandated into MTD ITSA from 6 April 2026, four quarterly submissions are required each tax year:

• Q1 (6 April – 5 July 2026): deadline 7 August 2026

• Q2 (6 July – 5 October 2026): deadline 7 November 2026

• Q3 (6 October 2026 – 5 January 2027): deadline 7 February 2027

• Q4 (6 January – 5 April 2027): deadline 7 May 2027

These are quarterly summaries of income and expenses, not final tax bills. They do not replace the End of Period Statement or Final Declaration, which remain due by 31 January 2028.

Missing a quarterly deadline earns one penalty point. At four points, a £200 penalty is charged. Points expire after 24 months of full compliance.

National Insurance Contribution Deadlines

Class 2 NIC: Abolished from April 2024. No longer separately paid by sole traders.

Class 4 NIC: Calculated as part of self-assessment and paid with your January and July payments on account. There is no separate deadline for Class 4 NIC.

Voluntary Class 3 NIC contributions (to fill gaps in your National Insurance record) can be made at any time, but gaps in years that are about to become inaccessible should be addressed before April 2025 under the temporary extension.

Why Being Even One Day Late Is Costly

HMRC's penalty system is automatic and does not require a human decision. If you file one day late, the system issues a penalty notice without any discretion. You can appeal on the grounds of a "reasonable excuse" (serious illness, bereavement, software failure), but these appeals take time and are not guaranteed.

The safest approach, and the one advocated by every accountant, is to file well before the deadline. Filing in November for a January deadline means any errors can be corrected without time pressure. It also means any unexpected tax bill gives you two months to plan for payment.

Using MTD-compatible software keeps your records updated throughout the year, which makes filing at any time a much faster process. There is no longer any reason to scramble through bank statements in January.