Key UK Accounting Dates October 2026
October is a busy month in the UK tax calendar, with important deadlines covering Self Assessment, Corporation Tax, VAT, PAYE, National Insurance, CIS and PAYE Settlement Agreements.
For business owners and directors, it is also a useful month to start looking ahead. The 31 January Self Assessment deadline may still feel some way off, but getting your records and tax return organised now can make the end of the year considerably easier.
Below, we have rounded up the key UK accounting and tax dates for October 2026, who they apply to and what you need to do.
Key UK tax deadlines for October 2026
| Date | Deadline | Who it may affect |
|---|---|---|
| 1 October | Corporation Tax payment due for accounting periods ending 31 December 2025 | Limited companies |
| 5 October | Deadline to notify HMRC if you need to register for Self Assessment for the 2025/26 tax year | Newly self-employed people and others with an undeclared Self Assessment liability |
| 7 October | VAT return and payment deadline for VAT periods ending 31 August 2026 | VAT-registered businesses with the relevant VAT period |
| 14 October | CT61 return and payment for the quarter ended 30 September 2026 | Companies required to deduct Income Tax from certain payments |
| 19 October | PAYE, National Insurance and CIS payments due where paying HMRC by post | Employers and CIS contractors |
| 19 October | CIS monthly return due for payments made to subcontractors in the tax month ending 5 October 2026 | CIS contractors |
| 19 October | 2025/26 PAYE Settlement Agreement tax and Class 1B National Insurance payment deadline where paying by post | Employers with a PSA |
| 22 October | PAYE, National Insurance and CIS electronic payment deadline | Employers and CIS contractors |
| 22 October | 2025/26 PAYE Settlement Agreement tax and Class 1B National Insurance electronic payment deadline | Employers with a PSA |
| 30 October | Non-Resident Landlord Scheme quarterly return and tax payment for the quarter ended 30 September 2026 | Letting agents and certain tenants operating the scheme |
| 30 October | Plastic Packaging Tax return and payment for the quarter ended 30 September 2026 | Businesses registered for Plastic Packaging Tax |
| 31 October | Company Tax Return deadline for accounting periods ending 31 October 2025 | Limited companies with the relevant accounting period |
| 31 October | Paper Self Assessment tax return deadline for the 2025/26 tax year | Individuals filing Self Assessment on paper |
Important: deadlines can vary depending on your accounting period, payment method and circumstances. Always check the date shown in your HMRC account or speak to your accountant if you are unsure.
1 October 2026: Corporation Tax payment deadline
If your company’s Corporation Tax accounting period ended on 31 December 2025, the normal Corporation Tax payment deadline is 1 October 2026.
For companies with taxable profits of up to £1.5 million, Corporation Tax is normally payable nine months and one day after the end of the accounting period. Different rules can apply to larger companies that are required to make quarterly instalment payments.
It is worth remembering that paying Corporation Tax and filing your Company Tax Return are separate obligations with different deadlines. HMRC’s guidance on Corporation Tax payments explains the rules in more detail: Pay your Corporation Tax bill on GOV.UK.
5 October 2026: Register for Self Assessment
5 October 2026 is an important deadline if you need to complete a Self Assessment tax return for the 2025/26 tax year and HMRC does not already know that you need to file one.
This can include people who became self-employed during 2025/26, started receiving certain untaxed income or otherwise became liable to Self Assessment.
You may need to take action if, for example, you:
- started working as a sole trader;
- became a partner in a business partnership;
- received income that needs to be declared through Self Assessment; or
- previously registered for Self Assessment but did not need to submit a return for 2024/25 and now need to file again.
HMRC confirms that taxpayers who need to register for the previous tax year should tell HMRC by 5 October. You can check whether you need to register using the official guidance: Register for Self Assessment on GOV.UK.
What happens if you miss the 5 October deadline?
Missing 5 October does not mean you should wait until next year. Register as soon as possible. HMRC may charge a penalty where a failure to notify results in tax being unpaid, particularly if the eventual tax liability is also paid late.
The main Self Assessment filing and payment deadline for online returns for 2025/26 is 31 January 2027, so there is still time to get everything organised.
7 October 2026: VAT return and payment
Businesses with a VAT accounting period ending 31 August 2026 will generally need to submit their VAT return and make the associated payment by 7 October 2026.
The standard online VAT deadline is usually one calendar month and seven days after the end of the VAT accounting period. Different deadlines can apply if you use certain VAT schemes, including the Annual Accounting Scheme.
VAT-registered businesses normally need to submit a return even where there is no VAT to pay or where the business is due a repayment.
You can check the rules and your VAT deadlines through HMRC: Sending a VAT Return on GOV.UK.
