HMRC additional information form: a step by step guide for R&D claims

What the additional information form is

The additional information form is a mandatory online submission that must reach HMRC before or at the same time as the corporation tax return carrying an R&D claim. It is not optional, and it is not the same thing as the claim notification form, which new claimants must file within six months of the period end.

If the form is missing, HMRC removes the R&D claim from the return. The company is usually able to resubmit within the normal time limits, but the delay is real and the correspondence is avoidable.

What you need before you start

Company details including unique taxpayer reference and PAYE reference. The accounting period covered. Contact details for the senior internal officer responsible for the claim, which means a named person inside the company, not the adviser. Details of any agent involved in preparing the claim.

Then the numbers: qualifying expenditure split by cost category, and the split between the merged scheme and Enhanced R&D Intensive Support where both apply.

How many projects you must describe

The number of project descriptions required depends on how many projects are in the claim. With three or fewer, describe them all. With four to ten, describe those covering at least half of the qualifying expenditure, and at least three. With eleven or more, describe the ten largest by qualifying expenditure, again covering at least half of the spend, and at least three.

Choose the projects that are both large and technically strongest. The descriptions you submit are the ones HMRC will read first, and a weak description of a large project invites a compliance check on the whole claim.

What each project description must cover

The main field of science or technology. The baseline of knowledge or capability at the start of the project, which means what was already publicly available or readily deducible, not what your company happened to know. The advance sought in that field. The scientific or technological uncertainties faced. How the project sought to overcome them.

Write the baseline honestly and specifically. Most weak forms fail here, describing the company's starting point rather than the state of the field, which makes ordinary development look like an advance and puts the whole claim in doubt.

Mistakes that cause problems

Naming the adviser instead of a company officer as the responsible person. Filing the form after the return rather than before or with it. Cost figures in the form that do not reconcile with the return. Copying the same generic paragraphs across every project. Describing commercial novelty rather than technological uncertainty.

One more, easily missed: if a claim notification was required and was not filed, completing the additional information form does not rescue the claim for that period.

Where to go next

We prepare the technical narrative, the cost schedule and the additional information form as one piece of work, so the form says the same thing as the report behind it. Book a free review and we will check your deadlines and filings before anything is at risk.