What R&D records and data do I need to keep to make a claim?

Why record keeping matters

R&D tax relief sits within self assessment, so the responsibility is on the company to show that the work meets HMRC’s definition of R&D and that the costs are accurate. HMRC has been clear in its Guidelines for Compliance that robust, written records help you make a compliant claim and complete the required submissions, including the Additional Information Form (AIF).  

Higher scrutiny is not a bad thing. It protects the incentive and rewards companies that can clearly explain what they did, why it was uncertain and how the numbers were built.

There is no single template but there is a clear expectation

HMRC does not require one specific record keeping system or a single format. What they do expect is that you can evidence the technical story and evidence the costs, using records that are credible and created close to the time the work happened. In a compliance check, HMRC may ask for anything reasonably needed to evidence the claim, including details of the uncertainty, the advance, the method or plan, the steps carried out, and how you arrived at the qualifying costs.  

Start with the basics: what you must be able to show

Before you worry about formatting or the “perfect” evidence pack, focus on the few fundamentals HMRC will always come back to. Your records should let someone outside the business understand, without guesswork, what you were trying to achieve, why it was not straightforward and how you approached it.

Just as importantly, they should allow you to trace the numbers in the claim back to real source data, so the costs look measured and repeatable rather than estimated on the spot. If you can demonstrate these basics clearly, everything else in the claim becomes easier to prepare, easier to review and far less likely to trigger follow-up questions.

A defensible claim usually has three strands that tie together:

1) Why the work qualifies

You should be able to show the project sought an advance in science or technology, faced scientific or technological uncertainty, and followed systematic work to resolve that uncertainty. A good record set makes this obvious without needing a long narrative.  

2) Where the R&D starts and ends

Project boundaries matter. HMRC will often test where uncertainty was identified, when it was resolved, and what work followed after resolution. That boundary is what separates qualifying R&D from routine implementation.  

3) How the costs link to the activity

HMRC expects you to explain how you arrived at your qualifying costs. Your records should allow you to trace from the claim schedule back to payroll, invoices, and the ledger, and then back to the R&D activity those costs supported.  

The most useful records to keep

The strongest R&D claims are supported by records you naturally generate while doing the work, not documents created months later for the claim. HMRC is looking for a credible trail that shows what the technical uncertainty was, what you did to resolve it, who was involved, and how the costs you have claimed relate to that activity. You do not need a perfect system or a mountain of paperwork, but you do need consistency. If your technical story, project timelines and cost workings all point to the same reality, it becomes much easier for HMRC to follow your logic and close any review quickly.

Technical records that show uncertainty and iteration

Keep records that show what you tried, what you measured, what failed, and what decisions were made as a result. This might include design notes, lab notebooks, simulation outputs, test reports, trial logs, calibration records, engineering change notes, and technical decision logs. If your work is software based, version control history, pull requests, architecture notes, and issue trackers can all be useful when they show the uncertainty and the work done to resolve it.  

Project management records that show timeline and boundaries

Gantt charts, sprint plans, milestone trackers, release plans, project boards, and meeting notes are useful where they show when R&D work started, when it paused, and when it moved into delivery. This is especially important where a project spans more than one accounting period, because you need to be able to support what was still uncertain in the period you are claiming for.  

People and time records that support staff apportionment

HMRC does not require timesheets, but you do need a reasonable method and supporting evidence. Timesheets can work if people understand what qualifies. If you do not use timesheets, you can still build a credible approach using role descriptions, team allocation plans, sprint participation, ticket reports, test schedules, or monthly time declarations signed off by a technical lead. The goal is not perfection. The goal is a method you can explain and repeat.  

Financial records that make your numbers traceable

At minimum, keep a clear cost schedule plus the source records that support it: payroll reports for staff costs, invoices and contracts for third parties, ledger extracts for software, cloud and consumables, and reconciliations from your claim totals back to the trial balance. HMRC’s cost guidance also stresses that costs must be paid to qualify, so evidence of payment can matter in some reviews.  

How to organise your evidence

If HMRC opens a compliance check, a strong first response is usually structured and easy to navigate. A simple approach is to keep an “R&D evidence pack” per accounting period, with:

• A project list and short summaries
• Key technical evidence per project
• Staff time approach and support
• Third party and software cloud support
• A reconciliation back to payroll and the ledger
• Copies and confirmations of required submissions such as the Additional Information Form and claim notification where relevant  
  

You are not trying to overwhelm HMRC with documents. You are making it easy for them to verify the claim.

First time claimants

If you are claiming for the first time, you may not have perfect systems. That is common. What matters is showing careful judgement and building a clear evidence trail from the records you do have. It is also worth checking early whether you need to submit a Claim Notification Form (CNF), as first time and infrequent claimants can be caught by this requirement and missing it can invalidate the claim. HMRC’s guidance focuses on clarity and credibility, so start simple and improve your process each year rather than backfilling everything at the end.

Common record keeping mistakes

Weak claims often share the same patterns: generic narratives with no uncertainty, project lists that do not match the Additional Information Form, staff time allocations that look like blanket percentages, and cost schedules that do not reconcile cleanly to payroll and the ledger. A small amount of structure up front usually prevents a lot of pain later.