A company claiming R&D relief for an accounting period beginning on or after 1 April 2023 must tell HMRC in advance if it is claiming for the first time or has not claimed in the previous three years, using a claim notification form submitted no later than six months after the end of the period of account. Every R&D claim, whether or not notification was needed, must also be supported by an additional information form sent before or on the same day as the return. If either requirement is missed, the claim is invalid.
Where do these rules come from?
HMRC’s Corporate Intangibles Research and Development Manual at CIRD181000 sets out the framework. Claims to the merged R&D expenditure credit and to enhanced R&D intensive support (ERIS) sit in Part 9A of Schedule 18 to the Finance Act 1998. The additional information requirement is in paragraph 83EA of that Schedule, and advance notification comes from section 1142A of the Corporation Tax Act 2009 with the detail in the Relief for Research and Development (Content of Claim Notifications, Additional Information Requirements and Miscellaneous Amendments) Regulations 2023 (SI 2023/813). Sections 1042C and 1045A of CTA 2009 then bar a claim made after the notification period unless an exception applies.
The claim itself is made in the company tax return or an amendment to it, filed through the Corporation Tax online service, and the relief must be quantified when the claim is made. For background on the reliefs see the R&D tax relief overview.
Who has to submit a claim notification?
HMRC’s guidance says a claim notification form is needed for accounting periods beginning on or after 1 April 2023 if the company is claiming for the first time, or its last claim was made more than three years before the last day of the claim notification period. CIRD183000 lists the statutory exceptions where no notification is needed:
- the company made an R&D claim in the three years ending with the last day of the claim notification period, ignoring a claim for an accounting period beginning before 1 April 2023 made by an amendment submitted on or after 1 April 2023;
- the accounting period falls within the same period of account as another accounting period for which the company has made a claim or notification.
HMRC’s guidance adds that an earlier claim does not count if HMRC removed it from the return. A company that needs to notify can either submit the form or get the claim itself to HMRC, in a return or amendment, by the last day of the notification period.
How is the claim notification period worked out?
Under section 1142A, as explained in CIRD183000, the claim notification period starts on the first day of the period of account and ends six months after the end of that period of account. It is tied to the accounts period, not to the return filing date. HMRC’s examples:
| Period of account | Last day to notify |
|---|---|
| 1 January 2024 to 31 December 2024 | 30 June 2025 |
| 1 January 2024 to 30 June 2025 (two accounting periods) | 31 December 2025 |
Where the period of account is longer than 12 months, the same notification period applies to every accounting period within it, and one form covers them. A notification can be made from the first day of the period, so companies that expect to claim can notify early.
What goes on the claim notification form?
Schedule 1 to SI 2023/813, reproduced in CIRD183000, requires:
- the company’s registered name and unique taxpayer reference;
- the name, role, telephone number and email address of the company officer responsible for the accuracy of the information;
- details of each agent or adviser, including agent reference number, address and whether they act only on the R&D claim or on other tax affairs as well;
- the start and end dates of the accounting period and the period of account, the number of projects, and an overview of them.
HMRC’s guidance says agents include anyone who gave advice, analysed costs, helped prepare technical assessments or completed the forms or return. It also warns that the form cannot be accessed once sent, so a copy should be saved, and that HMRC emails a reference number that should be kept as evidence.
What does the additional information form ask for?
CIRD182000 says the information must be provided on or before the date the claim is made, for claims made on or after 8 August 2023, and at least once for each accounting period claimed. HMRC’s guidance is blunter: if the return and the form go on the same day, the form must be sent first, because a return received before the form will have its R&D claim rejected. A 16 month period of account needs two forms, one for each accounting period.
The form covers company details (UTR, employer PAYE reference, VAT number, SIC code), the senior officer and every agent, accounting period dates that must match the return, qualifying expenditure by category including contractors, externally provided workers and overseas costs, R&D intensity information for ERIS including connected companies, and project details. The number of projects to describe depends on how many are claimed:
- 1 to 3 projects: describe them all.
- 4 to 10 projects: describe at least 3 that together account for at least half of the qualifying expenditure.
- More than 10: the same rule, but if more than 10 would be needed to reach half, describe the 10 with the highest expenditure.
Each project description covers the field of science or technology, the baseline knowledge, the advance sought, the scientific or technological uncertainties and how the project tried to resolve them. CIRD182000 states that referring to documents outside the form, such as “see R&D report”, is not acceptable even if HMRC holds the report, and that incomplete or nonsense answers do not meet the requirement and raise the risk of an enquiry.
What happens if a claim is amended or moved between schemes?
CIRD182000 says a valid claim that is later amended does not need a new form, although HMRC suggests sending one for material changes such as adding or removing a project. A new form is required if the company claims under the other scheme in an amendment, for example moving from ERIS to the expenditure credit, and each time a claim is withdrawn and made again.
The general time limit for making or amending a claim is two years from the end of the period of account (42 months from its start for periods over 18 months), under paragraph 83E as described in CIRD181000. That is far later than the notification deadline, which is why companies relying on the claim time limit get caught. See amending a tax return for the mechanics.
How does the timing play out?
Illustration only. A company with a 31 March year end last claimed R&D relief in a return received on 15 January 2024. It now wants to claim for the year to 31 March 2027.
- Claim notification period: 1 April 2026 to 30 September 2027.
- Three year look back: the earlier claim counts only if made on or after 1 October 2024. A claim made on 15 January 2024 is outside the window.
- Result: the company must notify by 30 September 2027, or file the return including the claim by that date. If it waits until its normal filing deadline of 31 March 2028, the claim is invalid.
- Whenever it files, it must submit the additional information form first.
What mistakes cause invalid claims?
- Measuring the notification deadline from the corporation tax filing deadline rather than six months after the period of account ends.
- Assuming a past claim always removes the need to notify without checking the exact three year window.
- Filing the return a few minutes before the additional information form on the same day.
- Entering accounting period dates on the form that do not match the CT600.
- Answering project questions by reference to a separate report.
- Switching schemes in an amendment without a fresh form.
Weak forms also feed HMRC’s risk assessment; see R&D tax relief enquiries and, for the accounts side, accounting for R&D tax credits.
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Related Accountapedia entries
- Registering a new company for corporation tax
- Long first accounts: splitting into two tax returns
- Senior accounting officer duties
- Notifying uncertain tax treatments
- The CT600 company tax return explained
Sources
- GOV.UK: Manual page CIRD181000
- GOV.UK: Manual page CIRD183000
- GOV.UK: Tell hmrc that youre planning to claim research and development rd tax
- GOV.UK: Manual page CIRD182000
- GOV.UK: Submit detailed information before you claim research and development
Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.