R&D Tax Credits for Trade & Construction Businesses — Do You Qualify? (2026)

What R&D Tax Relief Actually Is

R&D tax relief is a Corporation Tax relief. It is only available to limited companies that pay (or would pay) Corporation Tax — sole traders and ordinary partnerships cannot claim it. It rewards companies that carry out genuine research and development by reducing their tax bill, or in some cases producing a payable credit.

The critical point — and the one the claims companies gloss over — is the definition of R&D for tax purposes. It is not "anything new to your business", "a tricky job", "a one-off design" or "the first time we've done it". For tax purposes, R&D means a project that seeks to achieve an advance in science or technology by resolving scientific or technological uncertainty — uncertainty that a competent professional working in the field could not readily resolve. Routine work, no matter how skilled, complex or commercially valuable, is not R&D.

The Merged Scheme (RDEC) — What Changed

For a long time there were two schemes: the SME scheme (more generous, for smaller companies) and RDEC (Research and Development Expenditure Credit, originally for larger companies). For accounting periods beginning on or after 1 April 2024, these were merged into a single RDEC-style scheme that most companies now use.

Alongside the merged scheme there is enhanced support for R&D-intensive, loss-making SMEs — sometimes called ERIS (Enhanced R&D Intensive Support). A company can qualify as R&D-intensive where qualifying R&D spend makes up a high enough proportion of total expenditure, which can give a more generous payable credit for genuine, research-heavy small companies.

Rates, thresholds and the exact mechanics change frequently and depend on your accounting period, whether you are profit- or loss-making, and whether you meet the R&D-intensive test. Do not rely on a headline percentage you read online. Confirm the current rates and rules with HMRC guidance or a qualified adviser before assuming any figure.

The Genuine Qualifying Test

HMRC's guidelines (set out in the DSIT/BEIS guidelines and CIRD manual) frame it around four questions. To have a genuine claim, a project must:

• Seek an advance in overall knowledge or capability in a field of science or technology — not just an advance for your own company.
• Encounter scientific or technological uncertainty — a point where it is genuinely not known whether something is feasible, or how to achieve it.
• Involve work to overcome that uncertainty — systematic attempts, testing, iteration.
• Be uncertainty that a competent professional in the field could not readily deduce or resolve.

That last point matters enormously in the trades. If an experienced structural engineer, building services designer or competent professional could work out the answer from existing knowledge and standard methods, there is no qualifying uncertainty — even if the job was hard, time-consuming, or new to you.

Examples That Might Genuinely Qualify

Real, qualifying R&D does exist in construction and engineering — but it tends to sit with specialist firms doing genuinely novel technical work, not general contractors doing standard installs. Examples that could qualify, if the technological uncertainty is real and documented:

• Developing a novel modular or offsite build method where it was genuinely uncertain whether the structure would perform, and no off-the-shelf solution or standard method existed.
• A bespoke engineering solution to a problem the industry had not solved — for example a new connection detail, foundation technique or temporary works approach where the outcome was genuinely in doubt.
• Developing or adapting a new material, composite or process (for instance a low-carbon concrete mix or a new fixing system) where you could not know in advance whether it would work and had to experiment to find out.
• Creating bespoke software or control systems to solve a technological problem that off-the-shelf products could not.

In every case the key is genuine technological uncertainty resolved through systematic work — and you must be able to evidence it. A vague claim that "we innovated" will not survive an HMRC enquiry.

Examples That Do NOT Qualify (Most Trade Work)

This is where claims companies have caused real damage. The following are not R&D, no matter how they are dressed up:

• Standard installations — fitting a kitchen, rewiring a house, installing a heating system, laying a patio. Skilled work, but no scientific or technological advance.
• Cosmetic and finishing work — plastering, decorating, tiling, landscaping.
• Applying known techniques to a new project — using established methods, materials and products in the usual way, even on a complex or prestigious site.
• "Difficult" or "first-time-for-us" jobs — commercial or scheduling difficulty, an awkward site, or simply not having done something before is not technological uncertainty.
• Meeting building regulations or a client's spec using standard solutions — that is good practice, not research.
• Design and detailing that a competent professional could produce using existing knowledge.

If a competent professional in your field could have worked it out with existing knowledge and standard methods, it is not R&D — full stop.

Qualifying Costs (If You Do Have a Genuine Project)

Where a genuine R&D project exists, only certain categories of cost count, and only the portion attributable to the qualifying activity:

• Staff costs — gross salary, employer's NIC and employer pension contributions for staff directly engaged in the R&D, apportioned to the time spent on it.
• Subcontractors — payments to subcontractors carrying out qualifying work, subject to restrictions and (under the merged scheme) rules about where the contracted R&D "belongs".
• Consumables — materials and items physically consumed or transformed in the R&D, plus a proportion of light, heat and power. Note: materials that end up in a finished, sold building or product can be restricted.
• Software used directly in the R&D.
• Some data and cloud computing costs used for the qualifying activity.

Working out the qualifying proportion accurately — and excluding the routine production work — is exactly where amateur claims go wrong.

The Big Warning: Claims Companies and HMRC Enquiries

For several years, "R&D claims companies" cold-called trade businesses promising large tax refunds for a percentage of the claim — often 20–30%. Many filed weak, exaggerated or simply invalid claims, took their cut, and left the company carrying the risk. HMRC responded with a major crackdown.

Things you must know if anyone is pushing you to claim:

• The Additional Information Form is mandatory. Claims must be supported by a detailed online form describing the projects, the uncertainties and the costs. Claims filed without it are not valid.
• Claim notification. For new claimants (and those who haven't claimed recently), you generally have to notify HMRC in advance, within a set window after the end of the accounting period, or you lose the right to claim for that period.
• HMRC opens enquiries. They have dramatically increased compliance activity on R&D, with a particular focus on construction. An enquiry can take a long time and demand detailed evidence.
• Penalties for overclaiming. If a claim is wrong, you may have to repay the relief plus interest and penalties — and the penalty can be higher if HMRC considers the error careless or deliberate. The claims company is usually long gone by then.

If it is your company's tax return, it is your company's liability. Be sceptical of anyone who guarantees a refund or tells you that ordinary construction work obviously qualifies.

Likely Qualifies vs Unlikely to Qualify

Practical, Cautious Tips

• Use a reputable specialist accountant, ideally a chartered or certified firm with genuine R&D experience — not a commission-only claims company.
• Be honest about the technological uncertainty. If you can't clearly articulate the scientific or technological problem and why a competent professional couldn't easily solve it, you probably don't have a claim.
• Keep contemporaneous records — project notes, test results, design iterations, time records — written at the time, not reconstructed years later for a claim.
• Don't let anyone exaggerate. Inflated claims are exactly what HMRC is targeting, and you carry the risk.
• Mind the deadlines — claim notification and the Additional Information Form have strict timing rules; missing them can cost you the relief entirely.
• If in doubt, don't claim. A small, dubious refund is not worth an enquiry, repayment, interest and penalties.

The Bottom Line

R&D tax relief is a legitimate, valuable relief for the small number of trade and construction companies doing genuinely novel technical work that resolves real technological uncertainty. For everyone else — the overwhelming majority of builders, electricians, plumbers and contractors doing skilled but routine work — it simply does not apply, and pursuing a weak claim is more likely to create a problem than a refund. Be sceptical, keep good records, and take advice from a qualified professional before you claim anything.

This article is general guidance only and not a substitute for professional advice. Rules and rates change; always confirm the current position with HMRC or a qualified adviser before acting.