Can a Solo Software Developer Claim R&D Tax Credits?

Yes. And more solo developers qualify than realise it.

The common myth is that R&D tax credits are only for pharmaceutical companies with lab coats and whiteboards, or for software teams with a dozen developers. That is not how HMRC sees it. A one-person software company can claim R&D tax credits if you are working to resolve a technical uncertainty that a competent professional in your field could not solve easily.

The challenge is proving it. Without a project manager, a technical lead, or a second developer to corroborate your story, the burden of evidence falls entirely on you. That is what this guide addresses. We are going to walk through what qualifies as R&D for a solo software developer, how to document your work, and what HMRC actually looks for in a claim from a one-person company.

This is R&D tax credits explained for the developer working alone. No fluff. No assumptions about team size.

What Qualifies as R&D in Software for a Solo Developer?

HMRC uses the same definition for a one-person company as it does for a team of fifty. The work must meet the BEIS guidelines (Department for Business, Energy and Industrial Strategy). These guidelines ask four questions:

  • Was there a technical uncertainty you could not resolve by applying standard industry practice?
  • Did you try to overcome that uncertainty through systematic investigation?
  • Did you attempt to resolve it using something that advanced the field of software development, not just your own knowledge?
  • If the work failed, would a competent professional in software recognise it as a genuine attempt?

For a solo developer, the most common qualifying activities include:

  • Building a new algorithm or data processing method that does not exist in any off-the-shelf library.
  • Integrating multiple complex systems where no standard API or middleware exists, requiring you to build a custom solution.
  • Optimising performance beyond what existing tools can deliver, where the standard approach would crash or time out.
  • Developing a novel user interface or interaction model that requires solving a genuine technical problem (not just making it look different).

The key distinction: building a standard CRUD app (create, read, update, delete) is not R&D. Building a CRUD app that must process 10,000 transactions per second on a £50/month server, where every standard framework fails, is R&D.

A real example. A solo developer in Shoreditch built a real-time data visualisation tool for financial traders. The standard charting libraries could not render updates faster than 200ms. The developer spent six months writing a custom WebGL renderer that achieved 15ms update times. That is R&D. The uncertainty was whether a single developer could achieve that performance without a team. The investigation was the iterative testing of different rendering approaches. The advance was a method that did not exist in any public library.

How to Prove Your Solo R&D Work Without a Project Manager

This is where most solo developers fall down. HMRC wants to see evidence that the work happened and that it was genuinely uncertain. Without a team, you are the only source of that evidence. Here is how to build it.

Keep a Technical Diary

Start a simple document. Call it "R&D Log" or "Technical Notes". Every time you hit a problem you cannot solve immediately, write down:

  • The date.
  • The specific technical problem.
  • What you tried that did not work.
  • Why it did not work.
  • What you tried next.
  • The outcome, even if the outcome was "still stuck".

This log is your primary evidence. It shows the systematic investigation. It shows the uncertainty. It shows the advance. Without it, you are relying on memory, and HMRC will not accept that.

Save Your Git History

Your version control history is a goldmine. HMRC will not ask for your full git log, but your accountant can use it to build the narrative. Branches that contain experimental code, abandoned approaches, or iterative refinements all support the claim. Do not squash or delete branches that relate to uncertain work.

Tag commits that relate to R&D work. A simple tag like "rd-attempt-1" or "rd-experiment-3" makes it easy to reconstruct the timeline later.

Document Your Research

When you look for existing solutions and find none, save the evidence. Screenshots of Stack Overflow searches that came up empty. Links to documentation that confirmed a library could not do what you needed. Notes from forums where other developers confirmed the problem was hard.

This proves the uncertainty was real. A competent professional would have looked for an existing solution first. You did. You found nothing. That is evidence.

Record Your Time Roughly

You do not need a timesheet app. A weekly note saying "Week 15: 30 hours on the rendering engine, still failing at 50ms" is enough. HMRC wants to see that the work was substantial and focused. A solo developer claiming 200 hours of R&D across a year is credible. Claiming 1,500 hours without any time records is harder to defend.

Our ICAEW qualified team at Holloway Davies recommends you estimate conservatively and document honestly. Overclaiming is the fastest way to trigger an HMRC enquiry.

What Does Not Qualify for a Solo Software Developer

Some activities look like R&D but are not. Common mistakes solo developers make:

  • Learning a new language or framework. Learning React or Python is not R&D. Building something novel in React that no one has built before might be. The distinction is whether the uncertainty is about your own learning or about the technical problem itself.
  • Routine bug fixing. Fixing a null reference exception is maintenance, not R&D. Fixing a race condition that only appears under extreme load, where no standard solution exists, is R&D.
  • Customising existing software. Changing the colour scheme or adding a field to a database is not R&D. Building a custom integration between two incompatible systems where no API exists is R&D.
  • Commercial uncertainty. "Will customers buy this?" is not a technical uncertainty. "Can we make this work at all?" is.

The test is always the same: would a competent software developer with the same resources have known how to do this without investigation? If yes, it is not R&D. If no, it probably is.

How Much Can a Solo Developer Claim?

The amount depends on whether your company is profit-making or loss-making.

Profit-Making Solo Company

If your software company is profitable, you claim the merged R&D tax credit scheme (for accounting periods starting on or after 1 April 2024). The benefit comes as a reduction in your corporation tax bill.

Example. Your company has £80,000 of taxable profit. You spent £30,000 on qualifying R&D costs (your own salary, software licenses, cloud computing costs for experimentation). Under the merged scheme, you can surrender that £30,000 at the applicable rate (the merged rate is around 15% for most companies, but check the exact percentage for your period). You get a cash credit or corporation tax reduction of approximately £4,500.

The exact calculation depends on whether you are R&D intensive (more than 30% of your total spend on R&D). If you are, the Enhanced R&D Intensive Scheme (ERIS) gives a higher payable credit. For a solo developer working on a single product, the intensive threshold is often met because your R&D spend is high relative to overheads.

Loss-Making Solo Company

If your software company is loss-making (common for early-stage solo developers), you can surrender the loss attributable to R&D for a cash payment. This is the most valuable option for pre-revenue companies.

Example. Your company has no revenue. You spent £40,000 on R&D (your director salary, cloud computing, software tools). Your company makes a loss of £40,000. Under the merged scheme, you can surrender the R&D element and receive a cash credit of approximately £6,000. That cash can fund your next round of development.

These figures are indicative. The exact rates change each year. Your accountant will calculate the precise benefit using the R&D tax credits calculator on our site.

What Costs Can a Solo Developer Include?

For a one-person software company, the eligible costs are narrower than for a larger company. You cannot include staff costs for employees you do not have. But you can include:

  • Your own salary (director remuneration) for the time spent on qualifying R&D. You must apportion your time between R&D and non-R&D work. If you spend 40% of your time on R&D, you include 40% of your salary.
  • Cloud computing costs for the specific resources used in R&D. AWS, Azure, or Google Cloud costs for experimentation servers, test environments, and data processing are eligible. General hosting for your live product is not.
  • Software licenses for tools used directly in the R&D work. IDE licenses, specialised libraries, and testing tools qualify. General business software (accounting, email) does not.
  • Consumables such as data sets purchased for testing, API credits consumed during experimentation, and cloud storage used for R&D data.
  • Subcontracted R&D if you pay another developer or agency to help with the uncertain work. The subcontractor must be unconnected to you (not a family member or another company you control) for the full 65% of cost to qualify.

You cannot include your own dividends, your office rent, your broadband bill, or your laptop purchase (unless you can show it was used exclusively for R&D, which is hard to prove).

How to Submit the Claim

The claim is made through your corporation tax return (CT600). Your accountant will prepare the claim and submit it alongside the return. You must also submit the R&D Additional Information Form (AIF) which describes the qualifying projects, the technical uncertainties, and the costs.

The AIF is the document that matters most for a solo developer. This is where you tell the story of your R&D work. HMRC will read this form and decide whether to accept the claim or open an enquiry. A well-written AIF with clear technical descriptions, a timeline of the investigation, and evidence of the uncertainty is your best defence.

Your accountant will help draft the AIF. But you need to provide the raw material: the technical diary, the git history, the research notes. Without that, the AIF will be vague, and vague claims get rejected.

Claims must be made within two years of the end of the accounting period. For a company with a 31 March year-end, you have until 31 March of the second following year. Do not leave it to the last month. The AIF takes time to prepare properly.

What Happens if HMRC Opens an Enquiry?

Enquiries into R&D claims are more common now than five years ago. HMRC has a dedicated R&D compliance team. They target claims that look inflated or poorly documented. A solo developer claiming £100,000 of R&D with a single paragraph of description is a red flag.

If HMRC opens an enquiry, they will ask for your technical evidence. This is where the technical diary, the git history, and the research notes pay off. If you have them, the enquiry usually closes quickly. If you do not, you may have to repay the credit plus interest and penalties.

Our advice: only claim what you can prove. If you spent 20 hours on a genuine technical uncertainty and documented it, claim those 20 hours. Do not inflate. The risk is not worth the reward for a one-person company.

Should You Use an Accountant for Your R&D Claim?

You can file the claim yourself. HMRC does not require an accountant. But the technical requirements of the AIF, the calculation of the credit, and the risk of enquiry make it sensible to use a specialist. A mistake in the calculation can cost you thousands. A poorly written AIF can trigger an enquiry that costs you months of time.

We handle R&D claims for solo developers regularly. The process is straightforward: you send us your technical notes and cost breakdown. We prepare the AIF and the corporation tax computation. You review and approve before submission.

If you want to discuss whether your solo software project qualifies, get in touch. We will tell you honestly whether it is worth pursuing. Not every project qualifies, and we will not push a claim that will not stand up to scrutiny.

Summary: The Solo Developer's R&D Checklist

  • Identify the specific technical uncertainty you faced.
  • Keep a technical diary showing your investigation.
  • Save your git history and tag R&D commits.
  • Document your research into existing solutions.
  • Apportion your time between R&D and non-R&D work.
  • Include eligible costs: salary, cloud computing, software licenses.
  • Work with an accountant to prepare the AIF and CT600.
  • Claim within two years of the accounting period end.
  • Only claim what you can prove.

R&D tax credits are not a loophole or a free grant. They are a legitimate relief for companies that invest in advancing technology. If you are a solo developer doing genuinely uncertain technical work, you should claim what you are entitled to. The key is documentation. Start today, even if your claim is months away. A few notes each week will save you hours of reconstruction later.

For more detail on the technical rules, read our R&D tax credits fundamentals page. For the full list of qualifying costs, see our glossary.