R&D Tax Relief: 30 September 2025 Deadline for March Year-End Companies

 

Companies with a 31 March 2025 financial year-end must act swiftly to meet a key compliance requirement: HMRC’s R&D Claim Notification Form must be submitted by 30 September 2025 if the company intends to claim Research and Development (R&D) tax relief for that period.

Why This Deadline Matters

HMRC introduced a mandatory pre-notification requirement for accounting periods beginning on or after 1 April 2023. This means that for the FY25 accounting period, companies must notify HMRC of their intent to claim R&D tax relief within six months of the end of their financial year.

Failure to submit this notification by the deadline will invalidate the R&D claim, regardless of eligibility or the quality of supporting documentation.

Who Must Submit the Notification?

You must submit the Claim Notification Form (CNF) if:

• Your company is claiming R&D tax relief for the first time.
• Your last R&D claim was made more than three years before 30 September 2025.
• You submitted a previous claim via an amended return for a period beginning before 1 April 2023, and it was filed after 1 April 2023 (these are excluded under transitional rules).

Even companies that have claimed in recent years may be caught out by these rules, especially if:

• They use different agents for R&D and general tax compliance.
• They filed amended returns rather than original submissions.

What Is the Claim Notification Period?

For a company with a period of account from 1 April 2024 to 31 March 2025, the claim notification period runs from:

• Start: 1 April 2024
• End: 30 September 2025

This six-month window after the year-end is the only opportunity to notify HMRC of your intent to claim.

What Information Is Required?

To complete the CNF, you’ll need:

• Your Unique Taxpayer Reference (UTR)
• Contact details for your internal R&D lead and any external agents
• The start and end dates of your accounting period and period of account
• A summary of planned R&D activities, showing how they meet HMRC’s definition of R&D (no evidence required at this stage)

How to Submit

The form must be submitted online via HMRC’s portal using your Government Gateway credentials. Once submitted, HMRC will issue a digital receipt confirming your notification.

Consequences of Missing the Deadline

If you fail to notify HMRC by 30 September 2025, you will lose the ability to claim R&D tax relief for the FY25 period. This could result in:

• Loss of tax credits
• Cash flow disruption
• Increased scrutiny from HMRC
• Potential penalties for non-compliance

Final Thoughts

The rules are complex and the consequences of missing the deadline are significant. If you’re unsure whether your company needs to notify HMRC, it’s best to consult your accountant.