Tax Diary: September to October 2024 Deadlines That May Still Matter

This tax diary outlines key UK tax deadlines that fell between September and October 2024. It is intended for taxpayers reviewing whether all obligations from this mid–tax-year period were dealt with correctly.

Even though these dates have passed, missed filings or payments linked to them can still result in penalties, interest, or HMRC follow-up action.

Key Tax and Payroll Deadlines for September and October 2024

• 1 September 2024 – Due date for corporation tax due for the year ended 30 November 2022.
• 19 September 2024 – PAYE and NIC deductions due for month ended 5 September 2024. (If you pay your tax electronically the due date is 22 September 2024)
• 19 September 2024 – Filing deadline for the CIS300 monthly return for the month ended 5 September 2024.
• 19 September 2024 – CIS tax deducted for the month ended 5 September 2024 is payable by today.
• 1 October 2024 – Due date for Corporation Tax due for the year ended 31 December 2023.
• 19 October 2024 – PAYE and NIC deductions due for month ended 5 October 2024. (If you pay your tax electronically the due date is 22 October 2024.)
• 19 October 2024 – Filing deadline for the CIS300 monthly return for the month ended 5 October 2024.
• 19 October 2024 – CIS tax deducted for the month ended 5 October 2024 is payable by today.
• 31 October 2024 – Latest date you can file a paper version of your 2023-24 self-assessment tax return.
• Why Mid–Tax-Year Deadlines Still Matter

Tax compliance is continuous throughout the year. Where an obligation was missed during September or October, HMRC may continue to treat the issue as outstanding until it is resolved.

Addressing any gaps sooner can help limit further charges and reduce the risk of later enforcement action, something often highlighted when records are reviewed later by a tax specialist in London or during HMRC compliance checks.

Common Obligations Around September and October

Deadlines during this period often relate to:

• VAT return submissions and payments
• PAYE and National Insurance reporting and payments
• Ongoing Self Assessment compliance
• Employer reporting obligations

Which obligations applied will depend on your circumstances, such as whether you were self-employed, an employer, or VAT-registered.

What Happens If a Deadline Was Missed?

If a tax deadline in September or October 2024 was missed, HMRC may have charged penalties or interest from the original due date.

In some cases, penalties increase over time while the issue remains unresolved. Even where no immediate notice was issued, HMRC can raise the matter later, particularly once figures are reviewed or queried by a tax advisor in London acting on your behalf.

Why It Is Worth Reviewing Now

Some taxpayers assume that missing less prominent deadlines has little impact. In practice, unresolved issues can accumulate and become more costly or complex to resolve later in the tax year.

Reviewing whether all September–October 2024 obligations were met can help avoid unexpected demands or compliance action.

HMRC Guidance on Late Tax Deadlines

HMRC explains how penalties and interest apply to late filings and payments on
GOV.UK.

Did You Miss Any September or October 2024 Deadlines?

Whether any action is required now will depend on which obligations applied to you at the time and whether they were dealt with correctly. For individuals and businesses in Kingston upon Thames and nearby areas such as Hampton Wick and Long Ditton, CIGMA Accounting can review your position and confirm whether anything remains outstanding or needs to be addressed.