R&D Claim Notification Form: Rules and Exemptions
Quick Answer
First-time and gap claimants need a Claim Notification Form for R&D claims on periods beginning on or after 1 April 2023. It must reach HMRC within six months after the period of account ends. For a 30 June year-end, that means by 31 December. Miss it and the claim is invalid.
For accounting periods beginning on or after 1 April 2023, HMRC requires companies that have not recently claimed R&D Tax Relief to submit a Claim Notification Form before the substantive R&D claim is filed. The form is sometimes called the Advance Notification Form (ANF) or simply the pre-notification.
It is a separate document from the Additional Information Form (AIF), which every R&D claimant must file regardless of history. The Claim Notification Form sits earlier in the process and applies to a narrower group.
To help UK SMEs work out whether they need to file, we have built a free Pre-Notification calculator that walks through the test in under two minutes. The deadline falls six months after the end of the period of account, well before the Company Tax Return is due, which is why it is so easy to miss. The rules below explain what the calculator is testing for and why the answer matters.
Who this applies to
The Claim Notification Form is required where:
- The company is making an R&D claim for an accounting period beginning on or after 1 April 2023, AND
- The company is a first-time claimant, or has not made a valid R&D claim in the three years ending on the last day of the notification period (a “gap claimant”).
Companies that have claimed regularly within the previous three years are generally exempt. The exceptions to that exemption are covered below.
The claim notification period: when the clock runs
The notification period begins on the first day of the period of account and ends six months after the end of the period of account. For a company with a 30 June year-end and a 12-month period of account, the notification period for the 2025-26 period runs from 1 July 2025 to 31 December 2026. This follows HMRC’s own example, where a period of account ending on 30 June has a notification period ending on 31 December.
Because the window opens on the first day of the period of account, the form does not have to wait until the year-end. A company can file for its current period as soon as that period begins, once the planned R&D activity is known.
The form is filed online through HMRC’s Tell HMRC you want to claim R&D tax relief service. It can be submitted by the company or by an agent acting on its behalf.
The information required on the form is limited: company UTR, agent details where one is used, named contacts at the company, the accounting period and period of account dates, and a high-level summary of the planned R&D activities. It is not a substantive technical narrative. The AIF carries that work.
Claim Notification Form deadlines by year-end
For first-time and gap claimants with a 12-month period of account ending on a month-end, the Claim Notification Form deadline is:
| Year-end | Claim Notification Form due by |
|---|---|
| 31 January | 31 July |
| 28 or 29 February | 31 August |
| 31 March | 30 September |
| 30 April | 31 October |
| 31 May | 30 November |
| 30 June | 31 December |
| 31 July | 31 January |
| 31 August | 28 or 29 February |
| 30 September | 31 March |
| 31 October | 30 April |
| 30 November | 31 May |
| 31 December | 30 June |
The deadline falls in the calendar year after the year-end for any year-end from 31 July onwards. A long or short period of account, or one ending part-way through a month, changes the date, so check those cases individually.
If your company is a first-time claimant, or you have not made a valid R&D claim in the previous three years, the form must reach HMRC by the relevant date. Miss the deadline and the right to claim R&D Tax Relief for that period is gone.
If a deadline has already passed without a notification, the window for that period has closed. The practical step is to make sure it does not happen twice: the window for the current period opened on its first day, and the form can be filed now.
Our free Pre-Notification calculator returns a yes or no in under two minutes for any year-end date you provide, with the notification deadline where one applies.
The 3-year exemption
A company is exempt from filing the Claim Notification Form if it has made a valid R&D claim in the three years ending on the last day of the relevant claim notification period.
For a 30 June 2026 year-end with a notification period ending 31 December 2026, the relevant 3-year window runs from 1 January 2024 to 31 December 2026. Any valid R&D claim submitted to HMRC during that window exempts the company from the notification requirement for the 2025-26 claim.
“Valid” matters. A claim that was withdrawn, rejected by HMRC, or never properly submitted does not count for the purpose of the exemption.
Two exceptions to the exemption (you still need to notify)
Even where a company has claimed within the previous three years, the Claim Notification Form must still be filed in two specific scenarios:
Exception 1: a previous claim was rejected by HMRC
Where HMRC rejected the company’s R&D claim by removing the R&D figures from the Company Tax Return (typically as the outcome of an enquiry), that claim is not “valid” for the purposes of the exemption. The company falls back into the notification requirement for any subsequent claim.
Exception 2: a pre-April 2023 amendment received on or after 1 April 2023
Where the company’s only recent claim was made by amending a Company Tax Return for an accounting period beginning before 1 April 2023, and the amendment was received by HMRC on or after 1 April 2023, that amendment does not count towards the exemption. The company must still file a Claim Notification Form for any accounting period beginning on or after 1 April 2023.
This second exception caught several companies during 2024 and 2025 that believed a recent amendment to an older period would carry them through. It does not.
Claim Notification Form vs Additional Information Form: a quick comparison
The two forms are routinely confused. Both are mandatory for companies that need them. They are not interchangeable.
| Issue | Claim Notification Form | Additional Information Form (AIF) |
|---|---|---|
| Who must file | First-time and gap claimants only | Every R&D claimant |
| In force from | Accounting periods beginning on or after 1 April 2023 | All claims submitted on or after 8 August 2023 |
| Filing window | From the first day of the period of account until six months after it ends | Before the Company Tax Return containing the R&D claim is filed |
| Example: 30 June 2026 year-end | By 31 December 2026 | Before the CT600 is filed (CT600 due by 30 June 2027) |
| Information required | Light: company UTR, contacts, period dates, project summary | Substantive: project descriptions against DSIT R&D guidelines, qualifying costs by category, named senior officer |
| Submitted via | gov.uk service | gov.uk service |
| Effect of missing the deadline | Claim is invalid for that accounting period | Claim is invalid; HMRC removes R&D figures from the CT600 |
Worked example
A UK manufacturing company has a 30 June 2026 year-end. The company has never claimed R&D Tax Relief before.
- Accounting period: 1 July 2025 to 30 June 2026.
- Period of account: same.
- Claim notification period: 1 July 2025 to 31 December 2026.
- Deadline to file the Claim Notification Form: 31 December 2026.
- AIF deadline: before the CT600 is filed (CT600 itself due by 30 June 2027).
If the company files the Claim Notification Form on or before 31 December 2026 and the AIF before the CT600, the claim can proceed in the normal way. If the Claim Notification Form is not filed by 31 December 2026, HMRC will treat the R&D claim as invalid, with no retrospective remedy.
How to check whether you need to notify
The test is straightforward in principle and easy to get wrong in practice. Three factors interact: the dates of any previous R&D claim, the dates of the current accounting period, and the validity of the previous claim (taking the two exceptions above into account).
Our free Pre-Notification calculator runs the test on the dates you provide. It asks for the current accounting period and the date of the company’s most recent R&D claim (if any), and returns a yes or no answer on whether a Claim Notification Form is required, with the notification deadline if it is. The calculator is free to use, requires no sign-up, and stores no company data.
For companies whose previous claim was amended, rejected or marginally inside the three-year window, the calculator surfaces the right question and the right deadline rather than leaving the company to interpret the rule cold.
What happens if you miss the deadline
The consequence is binary. A Claim Notification Form filed after the end of the notification period is out of time, and the R&D claim for that accounting period is invalid. HMRC will remove the R&D figures from the Company Tax Return.
There is no statutory mechanism to make a late notification good. The company cannot rectify the position by filing later, by paying a penalty, or by appealing to HMRC’s discretion. The relief for that accounting period is lost.
The only routes that remain are to claim for the next accounting period (subject to the same notification test) and, separately, to consider whether anything else in the company’s affairs justifies an HMRC challenge against the rejection. Neither restores the lost claim.
Lexmore’s View
The Claim Notification Form is a low-information, high-consequence filing. The information HMRC requires is minimal. The cost of missing the deadline is the full value of the R&D claim for that period.
For first-time claimants, the form is straightforward provided the deadline is in the diary. Better still, file it early in the period of account, once the planned R&D activity is known, rather than waiting for the year-end. For companies who have claimed before but whose claim history is broken (a gap year, an amendment, a rejected claim, a sale or restructure), the right answer on whether notification is required is rarely obvious and frequently wrong.
We built the Pre-Notification calculator because the question is asked often, the rule is technical, and the consequences of getting it wrong are out of proportion to the difficulty of the test. It is free, takes under two minutes, and produces a clear written answer for the period the company is asking about.
Clear deadline. Clear evidence. Clear claim.
References
- Tell HMRC you want to claim Research and Development (R&D) tax relief | gov.uk
- Submit detailed information before you claim R&D tax relief (Additional Information Form) | gov.uk
- Research and Development (R&D) tax relief: the merged scheme and enhanced R&D intensive support | gov.uk
- HMRC Corporate Intangibles Research and Development Manual (CIRD)
- Lexmore Pre-Notification calculator
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Frequently Asked Questions
Is the Claim Notification Form the same as the Additional Information Form?
No. The Claim Notification Form is filed earlier in the process and only by first-time or gap claimants. The Additional Information Form is filed before the Company Tax Return and is required for every R&D claim, regardless of history.
When is the deadline?
Six months after the end of the accounting period. For a 31 March 2026 year-end, the deadline is 30 September 2026.
What counts as a “valid” previous R&D claim for the exemption?
A claim that was properly submitted, accepted by HMRC, and not subsequently rejected. A claim that HMRC removed at enquiry, a withdrawn claim, or a claim made by amending a pre-1 April 2023 return with the amendment received on or after 1 April 2023, does not count for the exemption.
Can my agent submit the form on my behalf?
Yes. The form can be submitted by the company or by an authorised agent.
What if I file the Claim Notification Form but later decide not to claim?
There is no penalty for filing and then choosing not to proceed. The form indicates an intention, not a binding commitment.
Do I need to file a separate Claim Notification Form for each accounting period?
Yes, if the notification requirement applies to that period. The exemption is tested separately for each accounting period.
Where can I check whether I need to notify?
The HMRC service is at Tell HMRC you want to claim R&D tax relief. For a quick yes or no test based on your own dates, our free Pre-Notification calculator returns an answer in under two minutes. https://lexmore.co.uk/rd/pre-notification