Tax Diary: August to September 2024 Key Deadlines

This tax diary summarises key UK tax deadlines that fell between August and September 2024. It is intended as a reference point for taxpayers reviewing whether all obligations from that period were dealt with correctly.

Although these dates are now in the past, missed filings or payments linked to them can still result in penalties, interest, or HMRC follow-up until resolved.

Key Tax and Payroll Deadlines for August and September 2024

• 1 August 2024 – Due date for corporation tax due for the year ended 31 October 2023.
• 19 August 2024 – PAYE and NIC deductions due for month ended 5 August 2024. (If you pay your tax electronically the due date is 22 August 2024)
• 19 August 2024 – Filing deadline for the CIS300 monthly return for the month ended 5 August 2024. 
• 19 August 2024 – CIS tax deducted for the month ended 5 August 2024 is payable by today.
• 1 September 2024 – Due date for corporation tax due for the year ended 30 November 2023.
• 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.

What This Period Commonly Covers

Deadlines during August and September typically relate to ongoing tax compliance rather than major annual filing points.

Depending on your circumstances, obligations during this period may have included:

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

Why Historic Deadlines Can Still Matter

Tax obligations do not automatically fall away once a deadline has passed. Where a return was not filed or a payment was made late, HMRC may continue to treat the matter as outstanding.

This can lead to penalties, interest charges, or later compliance action if issues are not addressed, something that is often identified retrospectively during a review by a tax specialist in London or through HMRC checks.

What Happens If a Deadline Was Missed?

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

Even where no immediate penalty notice was issued, HMRC can raise the issue later through statements of account or compliance checks, particularly if the position has not been clarified with a tax advisor in London or similar professional.

Why It Is Worth Reviewing Now

Some taxpayers assume that missing less prominent deadlines has little impact. In practice, unresolved issues from any period can accumulate and become more difficult to deal with over time.

Reviewing whether all August–September 2024 obligations were met can help prevent unexpected costs or enforcement action later.

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 August or September 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 Fulham Broadway and nearby areas such as Walham Green and Sands End, CIGMA Accounting can review your position and confirm whether anything remains outstanding or needs to be addressed.