Knowledge & Insights
The Additional Information Form: getting disclosures right first time
The Additional Information Form (AIF) is more than a checkbox, it’s a structured disclosure that HMRC can use to understand your claim profile at a glance. When the AIF is aligned to your report and computation, processing tends to be smoother. When it isn’t, it can create avoidable follow-up questions.
This guide sets out how to complete the AIF in a way that is clear, consistent, and reviewer-friendly, without turning it into a legal treatise.
1) What the AIF is actually doing
Think of the AIF as HMRC’s structured “front page” for your claim. It helps them understand what you’re claiming for, how big it is, and what the claim is made up of, quickly.
It is not a replacement for the report, but it should not contradict it either. The strongest submissions make it easy for a reviewer to see that the AIF and report are two views of the same underlying position.
A good rule of thumb
If a reviewer reads only the AIF and then scans your report, nothing should feel “new” or surprising.
2) The “baseline” information to get consistent
A surprisingly high percentage of issues come from simple inconsistencies across the CT600, computation, report and AIF. Before you write anything, lock down the basics:
- Claim period: accounting period dates match everywhere.
- Scheme position: the correct scheme for the period (and your status) is reflected consistently.
- Project list: project names are consistent across AIF and report headings.
- Totals: qualifying expenditure totals reconcile across AIF, computation and internal working papers.
- Contact details: the right agent/company contact details are used (and kept current).
Keep a single “reconciliation sheet” that ties AIF totals to the claim model and to the computation figures. This makes last-minute reviews fast and reduces the risk of mismatched numbers.
3) Projects: naming, summaries & scope
The project section should be short, concrete and technically anchored. Avoid overly broad statements like “we built a new platform”, the value is in describing the uncertainty and the attempted advances.
What to include (and what to avoid)
Include
The core uncertainty, what was attempted, why it wasn’t readily deducible, and what the outcome was (even if partial).
Avoid
Marketing language, generic “innovation”, or long feature lists without the engineering/scientific problem underneath.
If you have multiple workstreams, keep project scoping consistent: either split by meaningful uncertainty domains or group related uncertainties under a single project with clear sub-sections (but don’t mix approaches year-to-year).
4) Costs: category logic & apportionments
The AIF captures cost category totals. Your job is to ensure those totals are grounded in a methodology that is easy to explain and consistent with how you described the work.
A simple way to frame your cost logic
- What was the cost used for? (R&D environment, prototyping, experimentation, build/test cycles, etc.)
- Who used it? (technical team vs wider business, and how the split is estimated)
- Why is the proxy reasonable? (and what constraints prevent perfect allocation)
Consistency matters more than precision
If your allocations are reasonable and consistently applied, they tend to be easier to defend than “perfect-looking” allocations that change year to year with no clear driver.
5) Subcontractors, EPWs & overseas work disclosures
Where your claim includes externally delivered work, your disclosures should match the reality of how delivery was structured, and, importantly, where the work was performed.
Practical disclosure approach
- Define the engagement type: EPW vs subcontractor and why.
- Explain the qualifying linkage: what uncertainty the supplier helped resolve.
- Location clarity: where the activity took place and how you have evidenced this.
- Apportionment basis: how you split qualifying/non-qualifying elements (SOW, milestones, invoice lines, etc.).
If you have a supplier who did mixed delivery, be explicit about what is included and why. Avoid “all-in” assumptions for externally provided work unless the evidence genuinely supports it.
6) Linked/connected companies and group context
Where ownership structures are more complex (or where there have been acquisitions, reorganisations, or group claims), ensure the AIF’s declarations and scheme position reflect the group reality for the period.
If you’re unsure, this is one area where it’s worth being conservative and documenting the rationale for the position you’ve taken, particularly where there are changes mid-year.
7) A simple quality check before submission
Before submission, run a quick cross-check across your CT600, computation, AIF and report:
- Do project names and counts match between the AIF and the report?
- Do category totals reconcile to your claim model and the computation?
- Does your methodology explanation support the cost profile shown in the AIF?
- Are externally delivered costs described consistently (type, location, apportionment)?
- Would the overall picture make sense to someone outside the business?
8) Common AIF pitfalls and how to avoid them
Most AIF issues are preventable. In our experience, the most common pitfalls include:
- Misalignment: AIF totals don’t reconcile to computation totals.
- Project inconsistency: project names or descriptions differ materially between AIF and report.
- Weak cost rationale: large cloud/software figures without any clear allocation basis.
- External work ambiguity: EPWs vs subcontractors mixed, or overseas work not clearly addressed.
- Last-minute edits: one document updated but not the others.
Want us to review your AIF before you submit?
We can sense-check alignment across the AIF, report and computation, and highlight practical edits that make the submission clearer and more consistent.
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