Key Dates

30 September 2025 - Corporation Tax returns due for accounting periods ended 30 September 2024.

30 September 2025 - Deadline for filing of accounts with Companies House for accounting periods ended 31 December 2024.

1 October 2025 - Companies bidding for Government contracts exceeding £5 million per year will be excluded from the procurement process if they fail to pay their suppliers within an average of 45 days from this date.

5 October 2025 - Deadline to notify HMRC of your potential liability for tax and National Insurance Contributions for the 2024-25 tax year. This requirement applies to businesses that started during the tax year, with notification due by 5 October following its end.

5 October 2025 - Deadline to notify chargeability and advise HMRC of the need to register for Self-Assessment for 2025/26 if you have not notified them previously.