Tax Diary: May to June 2025 Deadlines That May Still Matter

This tax diary highlights key UK tax deadlines that fall between May and June 2025. It is relevant for taxpayers reviewing whether all obligations from the early part of the tax year were dealt with correctly.

Even where these dates have passed, unresolved filings or payments linked to this period can still result in penalties, interest, or HMRC follow-up actionn, particularly where matters were not reviewed at the time with a tax specialist in London.

Key Tax and Payroll Deadlines for April and May 2025

• 1 May 2025 – Due date for corporation tax due for the year ended 30 July 2024.
• 19 May 2025 – PAYE and NIC deductions due for month ended 5 May 2025. (If you pay your tax electronically the due date is 22 May 2025).
• 19 May 2025 – Filing deadline for the CIS300 monthly return for the month ended 5 May 2025.
• 19 May 2025 – CIS tax deducted for the month ended 5 May 2025 is payable by today.
• 31 May 2025 – Ensure all employees have been given their P60s for the 2024/25 tax year.
• 1 June 2025 – Due date for corporation tax due for the year ended 31 August 2024.
• 19 June 2025 – PAYE and NIC deductions due for month ended 5 June 2025. (If you pay your tax electronically the due date is 22 June 2025).
• 19 June 2025 – Filing deadline for the CIS300 monthly return for the month ended 5 June 2025.
• 19 June 2025 – CIS tax deducted for the month ended 5 June 2025 is payable by today.

Why May and June Deadlines Still Matter

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

For many taxpayers, this period follows the start of the new tax year, when earlier oversights can begin to surface through statements, reminders, or compliance checks, sometimes prompting a discussion with a tax consultant in London once discrepancies are identified.

Common Obligations Around May and June

Deadlines during this period often relate to:

• Outstanding Self Assessment filing or payment issues
• VAT return submissions and payments
• PAYE and National Insurance reporting and payments
• Ongoing compliance and reporting obligations

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

What Happens If a Deadline Was Missed?

If a tax deadline in May or June 2025 was missed, HMRC may have applied penalties or charged interest from the original due date.

In some cases, penalties increase the longer an issue remains unresolved. Even where no immediate notice was issued, HMRC can still pursue the matter later, at which point some taxpayers choose to seek clarity from a tax advisor in London.

Why It Is Worth Reviewing Now

Some taxpayers assume that missing early-year deadlines has limited impact. In practice, unresolved obligations can carry forward and result in unexpected demands or enforcement action later in the year.

Reviewing whether all May–June 2025 obligations were met can help reduce risk and avoid additional costs.

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 May or June 2025 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 Wimbledon and nearby areas such as Raynes Park and Colliers Wood, CIGMA Accounting can review your position and confirm whether anything remains outstanding or needs to be addressed.