Tax Diary: April to May 2023 Deadlines That May Still Matter

This tax diary covers key tax deadlines that fell between April and May 2023 and is relevant for taxpayers who want to check whether any obligations from that period were missed.

Although these dates have passed, unresolved filing or payment issues linked to them can still result in penalties, interest, or HMRC follow-up action, even where the original figures were later revisited through routine accounting services in London.

Key UK Tax Deadlines for April and May 2023

• 1 April 2023 – Due date for Corporation Tax due for the year ended 30 June 2022.
• 19 April 2023 – PAYE and NIC deductions due for month ended 5 April 2023. (If you pay your tax electronically the due date is 22 April 2023).
• 19 April 2023 – Filing deadline for the CIS300 monthly return for the month ended 5 April 2023. 
• 19 April 2023 – CIS tax deducted for the month ended 5 April 2023 is payable by today.
• 30 April 2023 – 2021-22 tax returns filed after this date will be subject to an additional £10 per day late filing penalty for a maximum of 90 days.
• 1 May 2023 – Due date for corporation tax due for the year ended 30 July 2022.
• 19 May 2023 – PAYE and NIC deductions due for month ended 5 May 2023. (If you pay your tax electronically the due date is 22 May 2023).
• 19 May 2023 – Filing deadline for the CIS300 monthly return for the month ended 5 May 2023. 
• 19 May 2023 – CIS tax deducted for the month ended 5 May 2023 is payable by today.
• 31 May 2023 – Ensure all employees have been given their P60s for the 2022/23 tax year.

Why Past Tax Diary Deadlines Are Still Relevant

Tax deadlines do not become irrelevant simply because time has passed. Where a return was not submitted or a payment was made late, the matter can remain open until it is resolved.

This means April and May 2023 deadlines may still affect you today if HMRC considers an obligation outstanding.

Common Obligations Around April and May

Deadlines during this period often relate to:

• Self Assessment filing and payment obligations
• VAT return submissions and payments
• PAYE and National Insurance reporting and payments
• Start-of-tax-year reporting requirements

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 from April or May 2023 was missed, HMRC may have issued penalties or charged interest.

In some cases, penalties increase over time until the return is filed or the payment is made. Even where no immediate penalty was raised, HMRC may still pursue the issue later.

Why It Is Worth Reviewing Now

Some taxpayers assume older deadlines no longer matter. In practice, unresolved issues often resurface through HMRC reminders, statements of account, or compliance checks.

Reviewing whether all obligations from April to May 2023 were met can help avoid unexpected demands or enforcement action.

HMRC Guidance on Late Tax Deadlines

HMRC provides guidance on late filing, late payment, and the penalties and interest that may apply on
GOV.UK.

Did You Miss Any April or May 2023 Deadlines?

Whether any action is required now will depend on which obligations applied to you at the time and whether they were handled correctly. For individuals and businesses in Wimbledon and nearby areas such as Wimbledon Park and Raynes Park, CIGMA Accounting can review your position and confirm whether anything remains outstanding or needs to be addressed.