Why Most Agency R&D Claims Fail at HMRC Review
You built something genuinely new. A custom analytics platform for clients. An automated content distribution system. A machine learning tool that predicts campaign performance. The technical work was real. The costs were real. But when HMRC asks for evidence, you have a problem.
Because you didn't document R&D activity as it happened.
I see this every year. Agency founders who spent six months developing proprietary software, who solved technical uncertainties that no off-the-shelf product could address, and who are now facing a rejected claim or a full HMRC enquiry. Not because the work didn't qualify. Because the paperwork wasn't there.
HMRC do not accept retrospective narratives. They want contemporaneous evidence. That means notes, emails, project logs, and technical specifications created while the work was happening, not reconstructed at year-end when your accountant asks for it.
This guide shows you exactly what to document, when to document it, and how to build a system that takes five minutes per week. No fluff. Just the practical steps that keep your R&D claim safe.
What Qualifies as R&D in an Agency Context
Before we talk about documentation, you need to know what counts. Many agency founders assume R&D tax credits are only for labs and pharmaceutical companies. That is wrong. The UK's R&D tax relief scheme covers any project that seeks to resolve scientific or technological uncertainty.
For agencies, qualifying activities typically include:
- Building custom software platforms or tools for internal or client use
- Developing proprietary algorithms for bidding, targeting, or optimisation
- Creating automation systems that replace manual processes in novel ways
- Integrating multiple systems where no standard integration exists
- Solving technical problems where the solution was not readily deducible
- Developing new data processing or analysis methods
The key test is whether a competent professional in your field would have known the solution in advance. If they wouldn't, you have technological uncertainty. That is the heart of a qualifying R&D project.
As specialist agency accountants working with digital agencies, we regularly see claims for work that founders dismissed as "just building stuff." If you wrote code that solved a problem no one had solved before, document it.
The Core Documents You Need to Keep
You do not need a dedicated compliance team. You need five types of records, kept consistently throughout the year.
1. Project Initiation Documents
When you start a new development project, write down what the problem was. What specific technical challenge were you trying to solve? What existing solutions did you rule out and why? What made this problem genuinely uncertain?
This can be a single page in Notion, a Google Doc, or even a Slack message to yourself. The key is the date. If HMRC see a document created in February describing a technical problem, and then see your project burn starting in February, the timeline holds together.
2. Technical Notes and Decision Logs
As the project progresses, record the dead ends. The approaches you tried that failed. The unexpected results that forced you to pivot. The technical decisions you made and why.
This is the evidence that proves you were resolving uncertainty. A straight line from A to B does not qualify as R&D. The detours, the failures, the moments where you said "that didn't work, let's try something else", that is the R&D.
3. Timesheets or Time Logs
HMRC want to see that the people working on qualifying projects actually spent time on them. Generic timesheets that say "development work" are weak. Timesheets that say "built custom attribution model for client X, resolved data matching uncertainty between Google Ads and CRM" are strong.
If you use Xero Projects, QuickBooks Time, or any job-costing tool, tag time entries to specific R&D projects. If you don't use timesheets, start. Even a weekly log in a spreadsheet is better than nothing.
4. Emails and Internal Communications
Some of the best R&D evidence lives in your email inbox and Slack archives. A thread where your lead developer explains to a colleague why a particular approach won't work, and proposes an alternative, is contemporaneous evidence of technical uncertainty.
Save these. Tag them. Create a folder called "R&D Evidence 2025-26" and drop relevant emails and Slack exports in there monthly.
5. Budget and Cost Records
You need to show what you spent. Staff costs, subcontractor costs, software licenses, cloud hosting, materials. Your accounting system should already capture this, but you need to link costs to specific R&D projects.
In Xero or QuickBooks, create a separate tracking category or project code for each R&D initiative. That way, when your accountant prepares the claim, they can pull a clean cost report rather than sifting through your entire P&L.
A Month-by-Month Documentation System
Here is a realistic system that works for a 10-30 person agency. It takes one person (typically a technical lead or project manager) about 30 minutes per month.
Month 1: Project Kickoff
Create a project initiation document. One page. Define the technical problem, the uncertainty, and why existing solutions don't work. Save it to a shared drive with the project name and date.
Set up a tracking category in your accounting software for this project. Tag any initial costs (software purchases, contractor deposits) to that category.
Month 2-5: Active Development
Every two weeks, spend 15 minutes writing a brief technical note. What was tried? What failed? What unexpected results appeared? What decisions were made and why?
If you use a project management tool like Jira, Linear, or Asana, export the ticket history at the end of each month. The tickets themselves often contain detailed technical discussions that qualify as contemporaneous evidence.
Save any significant email threads about technical problems. A five-email chain where your developer explains a bug and proposes a novel fix is gold.
Month 6: Project Completion or Milestone
Write a summary of what was achieved. Compare the final solution to the original problem. Note what changed along the way. This is not a marketing document, it is a technical record.
Run a cost report from your accounting system showing all costs tagged to this project. Save it alongside the technical summary.
Year-End: Handover to Your Accountant
Send your accountant the folder containing all project initiation docs, technical notes, timesheet extracts, email archives, and cost reports. If you have done the monthly work, this takes 20 minutes.
If you haven't, you are now facing the scramble. And the scramble is where claims fall apart.
Real Example: A Bristol-Based Digital Agency
One of our clients, a 14-person digital agency based near Bristol Harbourside, spent eight months building a custom bidding algorithm for their paid media clients. Off-the-shelf tools from Google and Meta could not handle the complexity of their client's multi-channel attribution requirements.
They documented every step. Project initiation doc in February. Bi-weekly technical notes in a shared Google Doc. Slack threads saved to a folder. Timesheets tagged to the project in Xero. Cost reports run monthly.
When they submitted their R&D claim, the total qualifying expenditure was £187,000. The corporation tax saving was approximately £35,500. HMRC did not raise a single query. The evidence was complete, contemporaneous, and clearly linked to qualifying activities.
Compare that to another agency we worked with who tried to reconstruct their R&D activity from memory six months after the project ended. HMRC opened an enquiry. The claim was ultimately reduced by 60% because they could not produce adequate contemporaneous evidence. The difference was documentation.
Common Mistakes Agencies Make
Mistake 1: Only documenting successes. HMRC want to see the failures. The approaches that didn't work. The dead ends. If your documentation only shows the final solution, it looks like routine development, not R&D.
Mistake 2: Using vague language. "We built a new tool" is not helpful. "We developed a custom data processing pipeline to handle unstructured campaign data from 14 API sources, where no existing integration solution existed" is helpful. Be specific about the technical uncertainty.
Mistake 3: Waiting until year-end. This is the most common mistake. By the time your accountant asks for R&D evidence, the technical staff have moved on to other projects. Memories fade. Slack messages get archived. Emails get buried. The contemporaneous evidence is gone.
Mistake 4: Not linking costs to projects. If your accounting system cannot separate R&D staff costs from routine client work, you will struggle to substantiate the quantum of your claim. Use project codes or tracking categories from day one.
Mistake 5: Assuming it only applies to software agencies. Creative agencies, marketing agencies, and PR agencies all qualify if they are developing novel technical solutions. If you built a custom analytics dashboard, an automated reporting system, or a proprietary measurement methodology, document it.
You do not need expensive R&D software. Most agencies already have the tools they need.
Notion or Confluence: Create a template for project initiation docs and technical notes. Standardise the format so your team knows what to write and where to save it.
Xero or QuickBooks: Use project codes or tracking categories to tag all R&D-related costs. Run monthly reports to check you are capturing everything.
Dext or Hubdoc: If you have receipts for R&D-related purchases (software licenses, cloud credits, hardware), upload them immediately and tag them to the relevant project.
Slack or Teams: Create a channel called #rnd-evidence or #technical-notes. Encourage your developers to post brief notes when they hit a significant technical problem. Export the channel quarterly.
Float or Spotlight Reporting: If you use cash flow forecasting or management reporting tools, build R&D spend into your monthly reviews. Seeing the costs accumulate in real time reinforces the habit of documenting the work.
When to Speak to Your Accountant
If you are planning any significant development work in the next 12 months, speak to your accountant before you start. They can help you set up the documentation framework, identify which activities are likely to qualify, and ensure your cost tracking is structured correctly from the beginning.
If your agency has already completed qualifying work in the current financial year and you have not been documenting it, start today. Go back through your emails, Slack archives, and project management tools. Pull whatever contemporaneous evidence exists. It will not be as strong as documentation created in real time, but it is better than nothing.
As specialist agency accountants who work exclusively with agency founders, we help our clients set up these systems before the work starts. If your contractor mix has changed, or you are taking on a major development project, ask your accountant before year-end. The cost of setting up documentation is trivial compared to the value of a successful R&D claim.
Contact us if you want to discuss whether your agency's current development work qualifies for R&D tax credits, and how to document it properly from day one.
