R&D Claim Notification Form: A Complete Guide for UK Businesses
If your business is planning to claim R&D tax relief, one of the most important steps is submitting your R&D claim notification form (CNF). Since April 2023, HMRC has made it a legal requirement for many companies to notify them in advance if they want to claim.
Getting this right can save you time, reduce the risk of rejection, and make the whole claims process much smoother. In this guide, we’ll walk through what the notification form is, who needs to submit it, the deadlines involved, and how to do it properly without falling into common traps.
What is an R&D Claim Notification Form?
The R&D claim notification form is the way your business tells HMRC that you intend to make a claim for research and development tax relief. Think of it as the “heads up” stage. It doesn’t replace your actual claim, but it positions your company as compliant from the start.
Key facts about the CNF:
Required for accounting periods starting on or after 1 April 2023. Must be submitted online through HMRC’s portal.
Deadline: within 6 months after your period of account ends, Missing it could mean losing the right to claim
Who Needs to Submit an R&D Claim Notification?
Not every business has to submit the CNF, but the rules are strict. You must notify HMRC if:
You’re making your first R&D tax relief claim
Your last claim was more than 3 years ago
You claimed within the last 3 years but don’t meet certain HMRC criteria
Example: If your company year-end is 31 March 2025, and it’s your first time claiming, you’ll need to submit the CNF by 30 September 2025.
What is the Deadline for Submitting the Notification?
The deadline is 6 months after the end of your period of account. If your financial year runs from 1 April 2024 to 31 March 2025, your notification deadline is 30 September 2025.
If your period of account is longer than 12 months, you still only submit one notification.
Missing the deadline usually means you cannot claim at all for that year, regardless of eligibility.
How to Submit Your R&D Claim Notification Online
Submitting the CNF is straightforward, but accuracy is critical. Here’s the step-by-step process:
Step 1: Access the Form
Log in to HMRC’s website with your Government Gateway ID.
If you don’t have one, register first.
Step 2: Fill in the Required Details
You’ll be asked for:
Unique Taxpayer Reference (UTR) same as used for your company tax return
Main contact details senior internal R&D contact responsible for the claim
Agent details if you’re using a tax advisor.
Accounting period dates start and end dates.
Period of account may differ from accounting period.
Planned R&D activities number of projects and how they qualify (no evidence needed at this stage)
Step 3: Submit the Form Online
Submit electronically through HMRC’s portal
Keep the digital acknowledgement receipt HMRC sends back
What Happens After Submission?
Once HMRC receives your notification form:
They verify the accuracy of your details
They check whether your company meets notification rules
If required, they may ask for clarification or additional information
They confirm whether your notification is valid
Submitting the CNF doesn’t guarantee your claim will be approved, but it ensures your claim can be considered.
Common Mistakes to Avoid on the R&D Notification Form
Many claims get delayed or rejected because of simple mistakes, such as:
Using the wrong UTR
Entering incorrect accounting dates
Missing authorised contacts
Submitting after the deadline
Tip: Double-check every field before submitting and keep a copy of the completed form for your records.
What if You Miss the Notification Deadline?
If you miss the deadline, HMRC will normally reject your claim. There is no formal appeal process.
However, in 2024 HMRC admitted to publishing incorrect guidance which misled some businesses. To fix this, they introduced a temporary easement:
If you were affected, HMRC may still accept late claims made between 1 April 2023 and 30 November 2024
To apply, you must email HMRC’s R&D Policy team with specific details
But outside this one-off easement, missing the deadline means you lose your right to claim.
Benefits of Early Notification
Notifying HMRC early brings several advantages:
Benefit Why It Helps Early planning Gives you more time to gather evidence and structure your claim Faster claims HMRC already knows you’re planning to submit, reducing processing delays Lower risk Early compliance reduces the chance of HMRC enquiries Strategic value Helps with financial planning and cash flow management Risks of Not Submitting a Notification
Failing to notify HMRC has serious consequences:
Claim rejection – your claim could be dismissed automatically
Delays – HMRC may freeze your tax credit payments
Increased scrutiny – risk of deeper investigation into your accounts
Penalties – in some cases, financial penalties and interest charges
Example: A manufacturing company that skipped notification had their £150,000 R&D claim delayed by 10 months due to HMRC enquiries. Cash flow suffered, and they faced additional compliance costs.
Real-Life Example: R&D Claim Notification Timeline
Let’s say your company year runs from 1 January 2025 to 31 December 2025.
1 January 2025 Claim notification period begins
31 December 2025 Period of account ends
30 June 2026 Final deadline to notify HMRC
If you submit your CNF in February 2025, you’ll have peace of mind and more time to prepare your actual claim.
R&D Claim Notification FAQs
Can I amend a notification once submitted? No. You can’t normally edit it, but you can contact HMRC if you spot a mistake.
Does notification guarantee claim approval? No. Your full claim must still meet HMRC’s R&D eligibility criteria.
Do I need a specialist to handle the notification? Not legally, but professional support ensures accuracy and avoids delays especially for first-time claimants.
What are the most common mistakes? Incorrect company details, missing authorised signatures, and late submission.
Get Professional Help With Your R&D Claim Notification
Submitting the notification form may seem simple, but errors can cost you thousands in lost tax relief or months of delay. Working with an R&D tax relief specialist ensures your form is accurate, timely, and fully compliant with HMRC rules.
Ready to submit your R&D claim notification with confidence? Book a free consultation today and find out how much R&D tax relief your business could claim.
