Tax Diary September/October 2026

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.

All Finance News

New registration rules for payrolling benefits in kind

From 6 April 2027, employers must payroll taxable benefits in kind and expenses in real time, including company cars, car fuel, vans, van fuel, and employer-provided medical benefits. Most other benefits will become subject to mandatory payrolling from April 2028, while employment-related loans and

READ MORE

New HMRC tax assessments for savings interest

HMRC is beginning to issue tax calculation letters (P800) and Simple Assessment notices (PA302) to collect any tax owed on bank and building society interest earned during the 2025-26 tax year. Some taxpayers may already have received a Simple Assessment for the 2025-26 tax year that did not

READ MORE