If you are running a tech startup in the UK, one of the first finance questions worth getting right is how tech startups can unlock R&D tax credits — because the numbers can be material, even for a pre-revenue company. We are talking about real cash back into the business, or a meaningful reduction in your corporation tax bill, in exchange for work you are already doing.

The problem is that R&D tax relief has become something of a contested space. HMRC has tightened its scrutiny considerably, and the scheme itself went through a significant overhaul in April 2024. A lot of the guidance circulating online either predates those changes or overstates what qualifies. The result is that founders either under-claim — missing out on relief they are legitimately entitled to — or make inflated claims that attract an enquiry and cost them more to resolve than the relief was worth.

Our view is straightforward: get the substance right first, then structure the claim around it. Here is how we think about it.

The statutory definition is narrower than most founders expect. To qualify, your project must seek an advance in science or technology — not just build something new for your business, but push forward what is possible in a given field. HMRC's own language is an "appreciable improvement" to overall knowledge or capability, not just your own.

For tech startups, this tends to mean genuine technical uncertainty: you set out to build something and could not be confident at the outset that it was technically achievable, or that the approach you chose would work. If a competent professional in the field could have told you at the start exactly how to do it, it probably does not qualify.

Excluded fields include the arts, humanities, and social sciences — economics falls in here — so a fintech startup building a new algorithm may qualify while one refining a business model almost certainly does not. From April 2023, mathematical advances are treated as science for R&D purposes, which is a genuinely useful change for companies working in machine learning, statistical modelling, or cryptography.

One thing we emphasise to every startup client: failed projects can still qualify. The test is whether you were genuinely trying to advance science or technology, not whether you succeeded. That framing often unlocks claims founders had written off.

From April 2024, the old SME and RDEC schemes were merged into a single framework for most companies. The headline credit rate under the merged RDEC scheme is 20% of qualifying R&D expenditure, which translates to approximately 15–16% after tax — a meaningful improvement over what was available under the old RDEC.

There is, however, an important carve-out for startups specifically. The Enhanced R&D Intensive Support scheme — ERIS — applies to loss-making companies that spend at least 30% of their total operating expenditure on qualifying R&D. For those businesses, the post-tax benefit is closer to 27%, which is considerably more generous than the standard merged rate.

In practical terms, this matters a lot for early-stage tech companies. If you are pre-revenue or in a growth phase where you are running at a loss and the majority of your spending is going into building the product, ERIS is likely the right scheme to be filing under. Getting this wrong — claiming under the merged scheme when ERIS applies, or vice versa — is one of the most common errors we see, and it can mean either leaving money on the table or triggering an enquiry.

One procedural point that catches companies out: a Claim Notification Form must be submitted to HMRC within six months of the relevant accounting year end for first-time claims or where there has been a gap of three or more years since the last claim. Missing this deadline means the claim cannot proceed, regardless of how strong the underlying R&D case is.

Staff costs are consistently the largest qualifying category for tech startups — salaries, employer's National Insurance contributions, and pension contributions for employees who are directly engaged in R&D activity. The key word is "directly": administrative, sales, and management time generally does not qualify, and HMRC has become increasingly sceptical of claims where more than 90% of an employee's time is attributed to R&D. If you are claiming high percentages of a developer's time, contemporaneous records — timesheets, sprint logs, project management exports — make a significant difference.

Contractors and externally provided workers can also be included, but only where the R&D intent is clearly documented and the arrangement is structured appropriately. Subcontracted work has its own rules, and these changed under the April 2024 reforms, so any existing approach should be reviewed against the current legislation.

Other qualifying costs include consumables used up during the R&D process, software licences directly used in the qualifying activities, and — under certain conditions — cloud computing costs. Costs that are commonly included but often should not be include general IT infrastructure, project management software used across the whole business, and any expenditure that is also being subsidised by a grant, where specific rules apply.

The practical message is to start capturing this information at the time, not retrospectively. Contemporaneous records are far more defensible than reconstructed timelines put together twelve months later when the claim is filed.

In the 2023–24 tax year, HMRC adjusted or rejected approximately 77% of the 9,700 claims it took into formal enquiry. That is not an argument against claiming — it is an argument for claiming properly.

The most common reasons for rejection cluster around a few themes. First, the project description does not demonstrate genuine technical uncertainty: it reads like a product development narrative rather than a technical one. HMRC's guidance is clear that the narrative should articulate the baseline state of knowledge at the start, the specific advance being sought, the uncertainties encountered, and the evidence of how they were investigated. A strong technical narrative addresses all four.

Second, advisors. HMRC now maintains an internal scoring system for R&D claim advisors, and using a firm with a poor track record increases the probability of scrutiny regardless of the underlying claim quality. The proliferation of R&D-specialist firms charging success fees without strong governance behind the claims has contributed directly to HMRC's current posture. We would always recommend working with an accountant who can defend the claim in an enquiry, not one who disappears if questions are raised.

Third, inflated costs — particularly staff time. As noted above, attributing an unrealistically high proportion of a developer's time to qualifying R&D, without supporting documentation, is a red flag. Timesheets or structured time-tracking are the simplest mitigation.

The startups that get R&D claims right consistently tend to have one thing in common: they treat the documentation as an ongoing process, not an annual scramble. That means logging technical challenges, recording experiments and dead ends, and capturing developer time in a format that is usable at year end.

For cloud-first businesses — which describes most of the tech startups we work with — this does not have to be onerous. Project management tools like Jira, Linear, or Notion already capture a significant amount of the information you need. The gap is usually converting that operational data into a coherent technical narrative that maps to HMRC's criteria.

We would also recommend getting an accountant involved before the claim is filed, not after the year end. The structure of the business — how contractors are engaged, how software licences are allocated, whether the company is likely to qualify for ERIS — can all be planned for in advance, and a well-structured claim from year one establishes a defensible baseline for every year that follows.

One final point: R&D tax credits sit alongside other reliefs and funding sources. If you are also receiving Innovate UK grants or SEIS/EIS investment, the interaction with R&D claims needs to be managed carefully. The rules here are specific and the two should never be treated in isolation.