What the rule is
For accounting periods beginning on or after 1 April 2023, HMRC’s guidance requires a claim notification form where you are claiming R&D relief for the first time. It also requires one where your last claim was made more than three years before the last date of the claim notification period. The manual anchors the window in statute: the period begins with the first day of the period of account and ends six months after the end of it.
The consequence of missing it is stated without softening: if you do not submit a required notification in time, your claim will be invalid.
Who it actually catches
Three groups, in practice:
- Genuine first-timers. The startup filing its first claim, which is why the rule leads every conversation on startups and early-stage companies.
- Lapsed claimants. Companies that claimed years ago, stopped, and assume they can simply resume. The three-year look-back is measured to the end of the notification window, and an old claim can be further away than memory suggests.
- Companies that claim late by habit. A company that historically amended claims into returns near the two-year deadline can find that its “last claim” falls outside the three-year reach when the next notification window closes. There is also a statutory disregard: any R&D claim for an accounting period beginning before 1 April 2023, made in an amendment submitted on or after 1 April 2023, does not count as a prior claim at all, so a recent-looking amended claim can still leave you needing to notify. Claim timing and notification timing interact, and the safe habit is simply to notify whenever the requirement is arguable.
How to make it a non-event
Notification is administrative, not technical: company details, the period, and basic claim information, submitted through HMRC’s online form. The failure mode is never difficulty; it is nobody owning the date. So:
- Put the notification deadline in the compliance calendar the day the accounting period starts, alongside the filing deadlines.
- If the year might contain qualifying R&D, notify. It costs little and commits you to nothing.
- Do not let the claim decision wait for the tax return cycle. The return can wait two years; the notification cannot.
The next document in the chain, mandatory for everyone rather than just first-timers, is the Additional Information Form.
Frequently asked questions
We claimed R&D relief a few years ago. Do we still need to notify?
It depends on timing: notification is needed where you are claiming for the first time, or your last claim was made more than three years before the end of your claim notification period. Recent, regular claimants are generally outside it, but check the dates rather than the impression.
When exactly does our window close?
Six months after the end of the period of account the claim relates to. A company with a 31 December year end has until 30 June following. The window opens on the first day of the period, so you can notify early, and there is no advantage in waiting.
What if we miss the deadline?
HMRC's guidance is blunt: without a required notification, the claim is invalid. There is no published discretion to accept a late notification, which is why "we will decide at year end" is a dangerous claim plan for first-timers.
Does notifying commit us to claiming?
No. Notification preserves the ability to claim; it does not oblige you to. If the year ends and the honest answer is no claim, nothing further happens.