Not as a separate document — but the technical content is compulsory, and it now lives on a form. Every R&D claim made since 8 August 2023 needs an Additional Information Form, which demands, project by project, the field of science or technology, the baseline level of knowledge or capability, the advance sought, the scientific or technological uncertainties and how the project set about overcoming them. Without that information the claim is invalid. A separate R&D report is optional: HMRC’s guidance says you can send further supporting details in one, and names the claim methodology, the use of sampling and details of the competent professionals. So the question is not whether to write a report, but whether yours would carry anything the form does not.
What the form already makes compulsory
The requirement is statutory, in paragraph 83EA of Schedule 18 to the Finance Act 1998, inserted by Finance (No. 2) Act 2023. It applies to claims made on or after 1 August 2023 — in practice 8 August 2023 — and the trigger is the date the claim is made, not the accounting period, so a backdated claim filed now needs a form of its own.
How many projects have to be described depends on how many you are claiming for. With one to three, all of them. With four or more, at least three that together account for at least half the qualifying expenditure you are claiming. Where reaching half would take more than ten, the ten with the highest qualifying expenditure. Alongside the descriptions the form carries the qualifying cost breakdown, the senior internal contact responsible for the R&D, and the details of every agent involved in the claim. What goes in the Additional Information Form covers each field in turn.
The practical effect is that the old model — a long narrative document attached to a return, with the return itself saying little — no longer works. The statutory answers belong on the form, in the form’s own words.
What an optional report is actually for
Look at the three things HMRC names as fitting in a separate report and a pattern appears: none of them is the technical narrative. The claim methodology, the use of sampling and details of the competent professionals are what the form has no field for. A report is the place for the reasoning behind the claim rather than a second telling of the claim itself, and it goes to HMRC by email or online with the Company Tax Return.
That reframes the decision. A report earns its place when it carries material an officer would otherwise have to ask for, and not when it restates the form at greater length.
When a report earns its keep
Five situations, in our experience, justify one.
- Sampling. Where costs were sampled across many staff, cost centres or projects rather than built from the ground up, the method needs setting out — how the sample was chosen, why it is representative, how it was extrapolated.
- The coverage gap. Where the description thresholds mean only some projects are described but the claim covers all of them, a report is the only place the remaining projects appear at all.
- The competent professionals. Who they are, their qualifications and years in the field, what they were asked and how they reached their view. HMRC’s guidance frames the advance by what a competent professional working in the field would recognise, so naming yours removes an obvious first question.
- Apportionment that is not self-evident. A staff-time basis derived from something other than timesheets, or a cost allocation that needs an explanation, is better explained now than reconstructed under enquiry.
- A position you would rather HMRC read early. Contracted-out R&D, externally provided workers, overseas expenditure or reliance on a PAYE cap exemption — points where the analysis is arguable and the reasoning is worth showing.
Against that, a report that repeats the form in different words adds cost and reading time and nothing else. So does one written by someone who never spoke to the engineers, which reads exactly as it was made.
What a report does not replace
Two obligations sit outside it. The form’s questions have to be answered on the form: a claim is not saved by a report that answers them elsewhere. And record-keeping is a separate duty again. There is no R&D-specific statutory format, but a company must keep and preserve the records needed to deliver a correct and complete return until the sixth anniversary of the end of the period the return covers, and longer while an enquiry is open or can still be opened. What records you need sets out what that means in practice. HMRC’s own guidance asks for proportion rather than volume: there is no need to write a ten-page plan for a project where a page of bullet points covers all the steps.
HMRC checked around one in six claims in 2023-24, its latest published figure, and the form is the first thing an officer reads. Getting it right matters more than the length of anything attached to it. Our Additional Information Form guide explains what a well-prepared form contains section by section, and if a claim was filed for you and you have never seen the form that went with it, our free claim review will tell you what it says about the work behind it.
Sources
- Additional information you must submit before you claim R&D tax relief — the required project information (field of science or technology, baseline level of knowledge or capability, the advance, the uncertainties and how the project sought to overcome them); the project coverage rules for 1 to 3, 4 to 10 and more than 10 projects; the contact and agent details; and, under “if you want to send us more information”, that further supporting details may be sent in a separate R&D report covering the claim methodology, use of sampling and details of the competent professionals, by email or online with the Company Tax Return.
- CIRD182000: additional information requirement — paragraph 83EA of Schedule 18 to the Finance Act 1998, inserted by Finance (No. 2) Act 2023; applying to claims made on or after 1 August 2023, in practice 8 August 2023; that the claim is invalid where the required information is not provided; and that it is not acceptable to refer to documents or information held outside the AIF, for example “see R&D report”, even where HMRC already holds them.
- FA 1998 Sch 18 para 21 — the duty to keep and preserve records needed for a correct and complete return until the sixth anniversary of the end of the return period, extended while an enquiry is open or can still be opened.
- GfC3: recommended approach to claims and record keeping — records proportionate to the project, and no need for a ten-page plan where a page of bullet points covers all the steps.
- HMRC’s approach to R&D tax reliefs 2023 to 2024 — 9,700 compliance checks against around 61,000 claims received, the source of the one-in-six check rate.
This page describes the rules as they stood at the review date above, as general information rather than advice on your circumstances. For how that distinction works, see our terms; for an answer on your own facts, talk to us.