Since August 2023, every R&D tax credits claim in the UK has needed a completed Additional Information Form (AIF) before the company tax return is filed. Miss it, and HMRC won't process the claim at all, no matter how strong the underlying R&D is.
HMRC introduced the AIF to cut down on inaccurate and poorly evidenced claims, and to give the process a structured audit trail it didn't have before. Every answer you give feeds into how HMRC assesses your claim, so getting the form right isn't a box-ticking exercise, it's part of making sure your claim actually succeeds.
This article walks through exactly what the AIF asks for in each section, what separates a strong project description from a weak one, and how Tax Cloud's guided workflow takes you through the whole form step by step.
What is the Additional Information Form?
The Additional Information Form (AIF) is the form HMRC requires before it will accept an R&D tax credit claim. It asks for details about your company, your R&D projects, and the costs you're claiming, and it has to reach HMRC before your Company Tax Return.
It was introduced in August 2023 as a way to reduce spurious claims being made. To reduce error and fraud in the scheme, HMRC now requires companies to provide project and expenditure details, to check if the claim is qualifying. The AIF is used to assess the risk of a claim before it is investigated further by HMRC’s team.
The results of the AIF requirement are already showing up in HMRC’s statistics. Last year saw a decrease in the volume of claims made, particularly in the SME scheme which saw a 23% decline for claims for the 2022-23 period compared to the 2021-22 period. This suggests that ineligible claims are already being weeded out.
Am I affected by the AIF?
The AIF requirement applies to all R&D tax claims made on or after 8th August 2023. This goes for the SME scheme, the RDEC scheme and the merged scheme. Every company submitting an R&D tax credit claim must also submit an AIF.
Following the apparent success of the AIF in the R&D tax scheme, HMRC even introduced a similar requirement for other tax relief schemes, such as the creative tax relief schemes.
What general information do I need to provide?
Accounting Period
You must make a separate R&D tax claim for each accounting period, so it makes sense that each accounting period should have its own AIF.
However, you’ll need to submit two AIFs for an extended accounting period; one for the first 12 months and another for the following short accounting period.
Company Details
HMRC needs to know some basic information about your company:
- Unique Taxpayer Reference (UTR)
- employer PAYE reference number
- VAT registration number
- Standard industrial classification (SIC) code
If your company is registered in Northern Ireland, you'll also need to provide your Company Registration Number and your registered address as held at Companies House.
Contact Details
To reduce the chance of a third party making a claim on behalf of your business without your knowledge, you need to provide the contact details of who is responsible for the claim.
You should provide the main senior internal R&D contact who is responsible for the R&D claim. This is usually a company director or lead finance contact.
Any third-party agent involved in preparing or submitting the claim should also be included. This includes specialist R&D tax advisors (like us!), but also any accountants who have helped prepare the claim.
R&D Qualifying Expenditure
You’ll need to provide a summary of the expenditure for each scheme you’re claiming under.
In most cases, you’ll only be claiming under one scheme (SME scheme, RDEC scheme or the merged scheme). However, if you are claiming some projects under the SME scheme and some under the RDEC scheme, you’ll need to separate those out. If you claim under the merged scheme, you cannot claim costs under any other scheme.
The AIF requests totals for the expenditure in each cost category claimed and a total for the qualifying direct costs versus the qualifying indirect costs. You’ll also need to separate out the total costs per project later in the AIF.
Connected Companies
The AIF requires you to include the details of any connected companies. This is only relevant if they were connected within the accounting period being claimed for (even if it was only for a day!).
HMRC asks for this because your connected companies' R&D and total costs are used to work out whether your group meets the R&D intensity condition for the higher ERIS rate, not just as a general disclosure.
Enhanced R&D intensive support (ERIS)
The enhanced R&D intensive support (ERIS) scheme offers loss-making SMEs the opportunity to claim a higher rate of relief.
Companies can claim under the ERIS scheme if they:
- are an SME
- make a trading loss for tax purposes before relief is calculated
- meet the R&D intensity condition of at least 30% of total costs are R&D for accounting periods beginning on or after 1 April 2024 (or at least 40% for periods beginning before this date)
To prove that you meet the R&D intensity condition, you’ll need to use the AIF to provide:
- the company’s total relevant costs for the period
- connected companies’ relevant R&D and total costs
- the company’s qualifying R&D expenditure
What project information do I need to provide?
The main field of science or technology
Your R&D project must be in a field of science or technology. You should specify further than this; for example, “mechanical engineering”, “information technology” or “pharmaceutical development”.
The baseline level of science or technology
Since a key qualification criterion of the R&D tax scheme is having an advance in the field, you need to explain what the field looked like before so HMRC has something to compare your advance to.
This should be a description of the existing state of the art and the knowledge and capabilities in the field at the outset of your project.
You may want to discuss competitor technologies, or the outcomes of a literature review. If you’re improving on a specific product, explain its capabilities at the beginning of the project. If you’re developing something entirely new, describe what you knew before starting.
The advance in scientific or technological knowledge
An advance is crucial to your R&D being eligible. You need to show how you sought to improve upon the state of the art in the wider field. You may be able to quantify your advance (e.g., “ten times faster”, “half the amount of energy required”) or it may be intangible (e.g., “new secure method of passing information electronically”, “new knowledge in the field of pharmaceuticals”).
You should describe the advance in comparison to the baseline already outlined and it should be clear that your advance is “better” than the existing options.
The scientific or technological uncertainties
You should include the scientific and technological uncertainties you faced when trying to achieve your advance. It needs to be clear why your expert team could not easily work out how to achieve the advance.
The uncertainties should be relatively specific to the project. The limitations of the existing science or technology can be discussed here.
How your project seeks to overcome these uncertainties
This section should be a brief outline of the R&D activities completed in the period. There’s no need to go into too much detail; a description of the methods used to overcome the uncertainties, the tests conducted and their results, and the big changes you made based on those results should be enough.
HMRC should be clear on why the R&D project was not straightforward and whether the uncertainties were resolved. If they weren’t resolved, it should be clear why not.
Amount claimed per project
As discussed above, for each project claimed you need to provide a total of the expenditure.
How much do I need to write?
HMRC doesn't set a word count for the AIF, which is often more unsettling for claimants than a strict limit would be. The amount of text needed depends on the question, and the complexity and size of the project will affect how much you need to say. In practice, this means writing enough to answer each question completely, in plain English, and then stopping.
The difference between an answer that satisfies HMRC and one that invites a follow-up enquiry is specificity. A vague answer, however long, still reads as vague. A precise one, even a short one, gives HMRC exactly what it's assessing the claim for: a genuine advance, a genuine uncertainty, and evidence that your team worked to resolve it.
Here's what that looks like in practice, using the "scientific or technological uncertainty" question as an example:
Weak answer: "Company A wasn't sure its new inventory system would work well across multiple warehouses, so it did a lot of testing and development to get it right."
Strong answer: "At the outset, no existing inventory platform could reconcile stock counts across Company A's multiple sites in real time without a manual reconciliation delay of several hours. It wasn't established whether a distributed database architecture could maintain consistency across sites without introducing latency that would make real-time reconciliation impossible, given the read and write conflict rates typical of pick and pack operations. Company A tested three synchronisation approaches before resolving the conflict-handling method needed to keep read and write operations consistent under load."
The weak answer states that uncertainty existed. The strong answer shows it: what wasn't known, why it wasn't known, and what had to be tested to find out. That's the level of specificity every section of the AIF should aim for, not a target word count.
Using a specialist R&D tax adviser can help you navigate this question; when you use Tax Cloud, your answers have a character limit to keep you within a reasonable limit. Our expert team reviews your responses and guides you to a better description, if necessary.
How many projects do I need to describe?
If you’re claiming for 1 to 3 projects, you need to describe all of them.
If you're claiming for 4 to 10 projects, you need to describe at least 3 of them, and those you choose must together account for at least half of your qualifying expenditure.
If you have more than 10 projects and reaching that 50% threshold would mean describing more than 10 of them, you can instead describe your 10 highest-cost projects.
For claims which are made across both the SME scheme and the RDEC scheme, the above rules apply separately to the schemes. You’ll need to assess the number of SME projects you have and the number of RDEC projects you have, then apply the above rules to those totals individually.
For example, if you have 8 SME projects and 2 RDEC projects, you’ll need to provide project details for:
- at least 3 SME projects which cover at least 50% of the total qualifying costs
- the 2 RDEC projects
This will become less of a concern going forward, as claimants will be claiming through either the merged scheme or the ERIS scheme.
How do I submit an AIF?
As a representative of the company, you’ll need the Government Gateway user ID and password you used when you registered for Corporation Tax. You can submit using HMRC’s portal for the AIF.
You won’t be able to access the form once it’s been submitted, so save a copy before you submit it.
What’s the deadline to submit an AIF?
Unlike the claim notification form, there is no actual deadline for submitting the AIF. The only requirement is that it is submitted before the Company Tax Return (CT600).
The deadline to make a claim for R&D tax is two years after the end of the accounting period. If you submit your CT600 on the last day, you need to make sure you submit your AIF first.
If you don’t submit the AIF first, the R&D tax claim will not be accepted. If you submit your CT600 first, you’ll need to submit your AIF then resubmit the CT600 for the R&D tax credit to be accepted.
Who can submit the AIF?
Only representatives of the company or registered agents can submit an AIF for a company.
Do I need to submit supplementary information?
This is not a requirement, but you’ll find most specialist R&D tax agents will write up and submit an additional claim report. This report will include more detailed cost breakdowns and will pre-emptively answer some questions on project qualifications and methodologies used which may be asked in an R&D tax compliance check.
It’s easier to do this work when preparing the claim than months down the line, in the event of a compliance check. With increased levels of scrutiny from HMRC as they try to stamp out error and fraud in the scheme, it’s a good idea to prepare for the worst-case scenario while you’re gathering your project details, instead of scrambling at the last minute.
You can submit supplementary information via email or when you submit your CT600.
How can Tax Cloud help?
At Tax Cloud, we support your claim at all stages, from project identification to submission to HMRC. We review your input, advise changes where necessary and provide a framework for you to accurately record your costs within HMRC’s requirements. We’ll submit the AIF on your behalf as a registered agent.
Get in touch or call us on 0207 118 6045 to learn how we can assist you with your R&D tax credit claims.
