Two years on, are too many businesses missing out?

On 30 September 2026 we passed an important, and largely unnoticed, anniversary.

It was two years since the first major wave of Claim Notification Form (CNF) deadlines following the introduction of HMRC’s R&D tax relief reforms. Companies that failed to notify HMRC by the relevant deadline effectively lost their ability to make an R&D claim, regardless of whether their projects qualified or not.

Whilst advisers have spent the last few years arguing over technical interpretations and legislative nuances, I increasingly believe we’re focusing on the wrong issue.

The biggest victims of the Claim Notification Form are not tax advisers.

It’s start-ups and early stage scale-ups that are really paying the price!

The start-up awareness gap

A mature business typically has an accountant, tax adviser, finance director, and established compliance processes.

A start-up often has none of those things.

Many founders first discover R&D tax relief after speaking to an investor, fellow entrepreneur, incubator programme, or specialist adviser. Sometimes that conversation happens months or even years after the relevant accounting period has ended.

Before April 2023, that delay was rarely fatal.

Today it can be.

A fintech company might spend its first two years creating an advance in computer science whilst developing it’s new platform, finally becoming aware of R&D tax relief, only then discover that it is no longer entitled to claim because a Claim Notification Form should have been filed six months after the accounting period ended.

The R&D activity was genuine;

The expenditure was incurred and paid;

The innovation happened; but

The claim is dead.

Not because the company failed the R&D rules, because it missed an administrative deadline it never knew existed.

The trap hiding in the legislation for scale-ups

The position becomes even more problematic when companies believe they have claimed before and therefore assume a Claim Notification Form is unnecessary.

HMRC’s legislation specifically excludes certain historical claims when determining whether a company qualifies for the three-year exemption.

In particular, a claim for an accounting period beginning before 1 April 2023 must be ignored if it was submitted through an amended corporation tax return filed on or after 1 April 2023.

That sounds technical.

But in practice it means many companies can believe they have an established claims history when, for Claim Notification purposes, HMRC effectively pretends that history doesn’t exist.

Most scale-ups have absolutely no reason to know this.

Frankly, why would they? Fortunately this situation is becoming less of an issue, but it could still be affect companies until March 2029!

Even HMRC struggled to explain it

Perhaps the strongest evidence that the rules are challenging is that HMRC itself published incorrect guidance during 2024 and later introduced an administrative easement for businesses that may have relied upon it.

If experienced tax professionals were debating the correct interpretation, it is unrealistic to expect first-time claimants and founder-led businesses to navigate the rules unaided.

Why HMRC introduced the Claim Notification Form

To be fair to HMRC, the Claim Notification Form did not emerge from nowhere. The R&D tax relief regime had developed significant integrity problems.

Commentators such as Paul Rosser have highlighted cases where claims were allegedly submitted without directors fully understanding what had been claimed and, in some reported instances, where companies only became aware claims had been submitted after HMRC opened a compliance enquiry.

Similarly, commentary published by Rufus Meakin discusses HMRC’s increasing focus on adviser behaviour, transparency and fraud prevention within the R&D market.

The Claim Notification Form provides HMRC with earlier visibility of claimants, company officers and potential projects. HMRC now routinely send out e-mails to the officer to advise them a form was submitted and asking them to contact them if they didn’t authorise it. The Additional Information form mandataed project descriptions and project costs and  details advisers involved in claims.

Unsurprisingly, HMRC believes this helps identify high-risk claims and prevent abuse. We would agree!

Here’s the question though “Has the pendulum swung too far?”

This is where the debate should now be.

Not whether the Claim Notification Form is technically valid. Not whether advisers understand the rules.

But whether too many genuine claimants are being excluded.

Every fraudulent claim prevented is a positive outcome.

But every start-up engaged in eligible activities that loses relief because it had never heard of the Claim Notification Form represents a policy failure too.

The challenge for HMRC is that both statements can be true simultaneously.

Two years on

Two years after the first major Claim Notification deadline, my concern is not that specialist advisers misunderstand the rules.

My concern is that too many founders still don’t know the rules exist.

And if those businesses remain unaware of the requirement until after the deadline has passed, then the Claim Notification Form risks becoming less of an anti-fraud measure and more of a trap for the very companies R&D tax relief was designed to support.

Trying to make them aware is my mission for the next 24 months!