R&D Tax Credits in 2026: Tighter Rules, Bigger Opportunities | MCC Partners

R&D tax credits have been one of the most generous reliefs available to UK SMEs for the last twenty years. They have also been the relief most exposed to abuse, sloppy advice and, more recently, an aggressive HMRC compliance response. By 2026, the rules look very different to the gold-rush years of 2019 to 2022, but the underlying opportunity for genuinely innovative SMEs — including the engineering, manufacturing and tech businesses we work with across Kent — is still real.

Here is where the regime sits in 2026, what HMRC is actually checking, and the practical steps that separate a successful claim from a costly enquiry.

One scheme, two rates

Since 1 April 2024, most companies claim under the merged R&D scheme, which combines the old SME and RDEC regimes into a single “above the line” credit. The headline rate is 20% of qualifying expenditure, which translates into a post-tax benefit of around 15% for profit-making claimants and similar for loss-makers, depending on circumstances.

A separate enhanced regime, Enhanced R&D Intensive Support (ERIS), applies to loss-making SMEs whose R&D spend is at least 30% of total expenditure. ERIS claimants can still access an effective benefit of around 27%, which keeps the support meaningful for genuinely R&D-intensive start-ups.

For accounting periods beginning on or after 1 April 2024, almost every SME claim now sits inside the merged scheme. The ERIS “30% threshold” question is the first one we ask any client considering a claim.

What HMRC is actually looking for in 2026

HMRC’s compliance teams now open enquiries on a far higher proportion of R&D claims than they did before the 2022 crackdown. The estimates we see suggest one in five claims is selected for some level of review, and the threshold for opening an enquiry has clearly dropped.

The pattern of enquiries gives a useful steer on what HMRC cares about:

• Genuine scientific or technological advance. The work must seek to make an advance in a field of science or technology, not just be new to the company. “We built a website” is not R&D. “We solved a non-routine technical problem to deliver functionality others in the field could not” might be.
• Identification of the underlying uncertainty. HMRC expects to see a documented technological or scientific uncertainty that a competent professional could not readily resolve.
• Competent professional sign-off. Claims now need a named technical lead who can defend the work in HMRC’s language.
• Project-level documentation, not blanket descriptions. A two-page narrative covering a year of mixed activity is not enough. HMRC expects project-by-project descriptions.
• Supporting evidence trail. Time records, Jira tickets, Git history, lab notes, design iterations — the contemporaneous record matters more than a polished retrospective.

Mandatory pre-notification and the digital claim form

Two procedural changes that catch SMEs out:

1. Pre-notification. Most first-time claimants, and those who have not claimed in the last three accounting periods, must notify HMRC of their intention to claim within six months of the end of the accounting period. Miss this window and the claim is invalid, regardless of how good the underlying R&D was.
2. Additional information form. Every claim now requires a digital additional information form covering project descriptions, qualifying costs and competent professional details, submitted before or alongside the company tax return.

We have seen otherwise valid claims fall apart on the pre-notification deadline alone. If you think you might claim, register the intention early. The cost is zero and the protection is total.

Where SMEs are still leaving money on the table

The narrative around R&D in 2026 has tilted heavily towards risk. That is fair — HMRC’s response to abuse has been blunt. But in our practice we still see genuine SME claimants under-claiming because they have either been put off by the noise or have been advised badly:

• Software companies under-claiming on platform work. Building bespoke infrastructure, integration layers or performance optimisations that competent developers found genuinely difficult is qualifying R&D, not routine.
• Manufacturers and engineers ignoring shop-floor innovation. Iterative prototyping, tooling improvements and materials testing often qualify, even when they look like ordinary product development.
• Loss-making start-ups missing the ERIS threshold. Companies a hair under 30% R&D intensity sometimes restructure their cost base to qualify. This is legitimate planning, not avoidance.
• Subcontracted R&D rules misunderstood. The merged scheme changed who can claim when R&D is contracted out. Reviewing contracts can release significant additional benefit.

A claim process that survives HMRC scrutiny

The way we run claims for clients in 2026 looks more like a structured project than an annual tax filing:

1. Eligibility scoping. A 60-minute call with the technical lead and finance, focused on whether there is genuine technological uncertainty.
2. Pre-notification. Filed immediately if there is any prospect of a claim, well within the six-month window.
3. Project workshops. Short, structured interviews with the people doing the work, producing the project-level narratives HMRC expects.
4. Cost analysis. Mapping qualifying expenditure across staff, subcontractors, externally provided workers, consumables and software, with clear evidence for each.
5. Quality review. A second-pair-of-eyes review by a senior specialist, focused on whether the claim would survive an HMRC enquiry.
6. Submission and defence. The additional information form goes in alongside the CT600, with a stand-by plan for responding to HMRC queries within their deadlines.

The MCC Partners view

R&D in 2026 is harder to claim than it used to be, but it is still one of the most valuable reliefs available to ambitious UK SMEs. The companies that benefit consistently are the ones treating it as a structured discipline rather than a year-end paperwork exercise. The ones who are still chasing six-figure refunds from low-quality “R&D specialists” are increasingly meeting HMRC head-on. There is a clear right side of this line.

If you have a real innovation story, you can still claim with confidence. You just need to claim well.