Pre-notification for R&D tax relief was introduced in 2023, and applies to claims for accounting periods beginning on or after 1 April 2023. Companies that have not claimed before, or that have not submitted a claim within the previous three years, must notify HMRC of their intention to claim before they submit their return.
In our previous blog, we looked at what pre-notification involves and how to complete the Claim Notification Form (CNF). You can read Part 1 here.
In this part 2 blog, we focus on the practical side – how firms can manage the claim notification requirement in practice, what HMRC appears to be flagging as problematic and what best practice looks like when preparing and submitting CNFs.
Although the requirement has now been in place for over two years, we are still seeing claimants and advisers struggling to apply the rules in practice. As the March 2026 deadlines approach, making sure the right processes are in place to identify when a CNF is required, and to submit it on time, remains essential.
At its most basic the CNF only requires the following:
However, that last point is ambiguous at best. HMRC’s guidance asks for ‘a summary of the high-level planned activities… you do not need to include evidence on the claim notification form, but you’ll be asked to give additional information before you claim R&D relief on your return’.
How this section is answered will also depend on the point during the claim notification window at which the CNF is submitted – the later it is submitted, the more in-depth information will be available about what work was done during the claim period.
While HMRC has given little feedback about what they want to see in the CNF, there is some anecdotal information available about what they don’t want to see.
This includes:
HMRC has noticed instances where agents submit multiple CNFs for different companies, all with identical descriptions of the R&D. This may prompt further enquiries.
Some CNFs contain little more than “R&D was carried out.” Although such wording technically fits the requirement for “a summary of the high-level planned activities”, it is not as informative as HMRC would like to see and may be questioned.
A few forms have been submitted with placeholder or random text. These do not meet the requirements and will be rejected.
As with everything related to R&D tax relief, robust processes and accurate records are key to successfully submitting the CNF. Making sure that records are kept of each eligible company and when it submitted previous claims will enable the correct decisions to be made about whether a CNF is needed.
Processes should be put in place to track claim notification periods, identify which companies need a CNF and submit CNFs on time with the required information.
Alongside this, having processes in place for managing new clients and ensuring that all information about their previous claims is received and recorded is vital to ensure a seamless transition of R&D claim work.
Having said all the above, there’s no downside to simply submitting a CNF for all clients as a matter of course. HMRC does not penalise companies that submit a CNF but do not then go on to submit a claim, and doing this means that no claim will be accidentally missed.
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We recently presented a webinar covering the CNF rules, the nuance and grey areas around when pre-notification is required and steps to help mitigate against missed claims. You can watch the full recording by clicking below:
With stricter HMRC oversight, accountants and advisers need a process that leaves nothing to chance. WhisperClaims keeps you on track with tailored guidance, risk assessments and expert Advice Line support, helping you submit robust claims and stay confidently on the right side of HMRC.
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