Pre-notification for R&D tax relief – what you need to know

Author: Jen Badger Published: 1^st July, 2025

When HMRC introduced the requirement to pre-notify R&D claims in April 2023, the communication around it was patchy at best. Two years on, we’re still seeing a huge amount of confusion and repeated misunderstandings about when and how companies need to submit a Claim Notification Form (CNF), and what happens if they don’t.

With the September deadline for March 2025 year ends approaching just after the summer holidays, we thought it timely to revisit the rules and potential pitfalls of pre-notification.

What is pre-notification?

Since April 2023, some claimant companies have been obligated to inform HMRC about their intent to claim R&D tax relief through the submission of the Claim Notification Form (CNF).

Also informally referred to as the Advanced Notification Form (ANF), the CNF has to be submitted within the claim notification period, which runs from the first day of the relevant period of account to six months after the end of the period of account. For longer periods of account, this is the same for each of the accounting periods within the period of account i.e. the deadline for both accounting periods within the period of account is the same.

Who has to submit a CNF?

A company must submit a CNF if:

This is their first claim for R&D tax relief
Their last claim was submitted more than three years before the end of the claim notification period
The only claim they have submitted in the three years up to the end of the claim notification period:

- Was for an accounting period starting before 1^st April 2023 and was submitted by amending the tax return for the period on or after 1^st April 2023

- Was rejected by HMRC and removed from the Company Tax Return.

Companies that have submitted valid claims within the three years up to the end of the claim notification period do not have to submit a CNF.

What information is needed to complete a CNF?

The CNF is a fairly short form, and asks for a limited amount of data about the company and their R&D activities. The required company details are as follows:

The company’s UTR
Contact details of the main R&D contact within the company
The contact details of any agents involved in the preparation of the claim.
The accounting period and period of account start and end dates

So far, limited feedback has been shared by HMRC on what level of detail is expected, leaving advisers to make a best-efforts judgement based on timing and project visibility. How much detail to include has been the subject of a great deal of debate. On the one hand, given that the CNF can be submitted before any of the R&D work for the claim period has been carried out, HMRC cannot expect more than a brief summary of what the company intends to do during the year. On the other, most CNF forms are submitted after the year end and therefore it should be possible to give a good amount of detail about the projects, advances and uncertainties. As yet, very little feedback has been received from HMRC about CNF forms submitted so far and what level of detail is expected.

What happens if a CNF is not submitted?

If a CNF is required and not submitted, the claim is invalid, and HMRC will remove it from the company’s Corporation Tax Return. When talking to advisers and accountants preparing claims, it’s clear that many will have their own story, or be aware of recent scenarios, where a legitimate claim has been missed – not due to negligence, but because of the complexity and nuance in the rules.

A common example involves claims submitted as an amended return. These situations are easily overlooked, particularly where advisers believe a previous claim met the exemption criteria, only to discover too late that a CNF was required.

Taking it a step further, a hypothetical scenario could involve a company having submitted a seemingly valid earlier claim, and on that basis, choosing not to submit a CNF for the current period. If that earlier claim were later rejected following an HMRC enquiry, after the CNF deadline for the subsequent claim has passed, the company could find itself unable to submit the most recent claim, even though the R&D activity was fully eligible.

The reality is that even diligent companies and advisers can fall foul of the rules due to technicalities that were not clearly communicated when the requirements were introduced. That’s why having a clear process and up-to-date understanding of the legislation is so important.

Is there a way to mitigate this problem?

There’s a strong argument for submitting a CNF every year regardless, to ensure that no claim is missed, and indeed this is the policy of a large number of accountancy firms and R&D consultancies.

HMRC has given no indication that there are any negative consequences to submitting a CNF every year, and no feedback has been shared by those companies implementing this policy.

So, given the current enquiry rate, and the possibility of a previous claim being rejected after the CNF deadline has passed for a subsequent period, an annual submission may offer an added layer of protection.