For many companies, the R&D tax relief process no longer begins when the Corporation Tax return is prepared. Under the current rules, some businesses must tell HMRC in advance that they intend to make an R&D claim. If this step is missed where it is required, the claim may be invalid, even where the underlying project work and costs would otherwise qualify.
This makes R&D claim notification one of the most important deadline checks for any company considering R&D tax relief. It is particularly relevant for first-time claimants, companies that have not claimed recently, and groups where accounting periods, restructures or new subsidiaries could make the position less straightforward.
What Is R&D Claim Notification?
R&D claim notification is the process of notifying HMRC that a company intends to make a claim for R&D tax relief or expenditure credit.
The notification is separate from the Additional Information Form and separate from the Corporation Tax return itself. In other words, submitting the main R&D claim later does not fix a missed notification deadline if notification was required.
Who Needs to Notify HMRC?
A company may need to submit a claim notification form if it is planning to claim R&D tax relief or expenditure credit for an accounting period beginning on or after 1 April 2023 and either:
There are also situations where previous claims do not count for this purpose, including where claims were rejected by HMRC or where certain older-period claims were made by amending a return after 1 April 2023.
This is why businesses should not assume they are outside the rules simply because they have claimed R&D relief before.
When Is the Deadline?
The claim notification period starts on the first day of the company's period of account and ends six months after the end of that period.
For example, a company with a 12-month period of account ending on 31 December 2026 would usually have a notification deadline of 30 June 2027.
This deadline can arrive earlier than many businesses expect because it falls before the usual Corporation Tax filing deadline.
Why Does This Matter?
Missing the claim notification deadline can have serious consequences.
If notification is required and the company does not submit the form within the claim notification period, the R&D claim will be invalid.
That means the company may lose access to relief for that period, even if the underlying R&D activity was genuine and the expenditure was otherwise eligible.
This is especially risky for:
Common Reasons Companies Miss the Deadline
In practice, the deadline can be missed because responsibility for R&D claims sits between different people.
A finance team may assume the adviser will deal with the claim later. An adviser may not be appointed until after the notification deadline has passed. A company may also assume that the normal two-year Corporation Tax amendment window still gives enough time.
However, claim notification is a separate requirement.
It needs to be considered much earlier in the process.
What Information Is Needed?
The claim notification form requires company and claim details, including:
The form does not replace the need for a full R&D claim, supporting methodology or Additional Information Form.
It is an early notification step designed to tell HMRC that a claim is expected.
What Should Companies Do Now?
Businesses considering an R&D claim should check their notification position as early as possible.
Key questions include:
If there is any uncertainty, it is better to check the position before the deadline passes.
How TAP Can Help
At Tax Advisory Partnership, we can help businesses check whether they need to submit a claim notification form, identify the relevant deadline, and review whether their wider R&D claim process is on track.
We can also help assess whether the proposed project activity is likely to qualify, prepare the required supporting information, and identify any areas that may increase the risk of HMRC challenge.
Final Thought
The R&D claim notification requirement is easy to overlook, but the consequences of missing it can be significant. Companies should not wait until the Corporation Tax return is being prepared to think about R&D tax relief.
If your business is planning to make an R&D claim, or if you are unsure whether notification is required, now is the time to check.
👉 Need help reviewing your R&D claim position? Contact Tax Advisory Partnership to arrange an R&D claims health check.