Tax Diary September/October 2026
Key tax deadlines and dates for September and October 2026 including Corporation Tax, PAYE/NIC, CIS returns, and Self-Assessment paper return deadlines...
1 September 2026 – Due date for corporation tax due for the year ended 30 November 2025.
19 September 2026 – PAYE and NIC deductions due for month ended 5 September 2026. (If you pay your tax electronically the due date is 22 September 2026)
19 September 2026 – Filing deadline for the CIS300 monthly return for the month ended 5 September 2026.
19 September 2026 – CIS tax deducted for the month ended 5 September 2026 is payable by today.
1 October 2026 – Due date for Corporation Tax due for the year ended 31 December 2025.
19 October 2026 – PAYE and NIC deductions due for month ended 5 October 2026. (If you pay your tax electronically the due date is 22 October 2026)
19 October 2026 – Filing deadline for the CIS monthly return for the month ended 5 October 2026.
19 October 2026 – CIS tax deducted for the month ended 5 October 2026 is payable by today.
31 October 2026 – Latest date you can file a paper version of your 2025-26 self-assessment tax return.
Disclaimer
The information contained in this article is for general guidance on matters of interest only. It should not be used as a substitute for consultation with professional accounting, tax, legal, or other competent advisers. Before making any decision or taking any action, you should consult a Kingscott Dix professional.