What HMRC Means by an Advance in Science or Technology in Hydrogen and Storage
The UK Government has identified hydrogen as a priority sector in its Net Zero Strategy and published the UK Hydrogen Strategy, which explicitly acknowledges the need for R&D investment in electrolysis, fuel cells, and hydrogen storage. From a tax perspective, HMRC applies the BIS Guidelines on the Meaning of R&D for Tax Purposes without sector modification: the work must seek an advance in science or technology through systematic activity that resolves genuine uncertainty which a competent professional could not readily resolve from existing knowledge.
Hydrogen and storage companies sit at the intersection of chemistry, electrochemistry, materials science, electrical engineering, and thermal engineering. Each of these is in scope under the BIS Guidelines. The typical qualifying claim for a hydrogen company combines materials science (catalyst and membrane development), systems engineering (electrolyser stack and balance-of-plant design), control and power electronics, and software (digital twin modelling, predictive degradation, grid-integration algorithms). Most early-stage companies in this sector are loss-making and ERIS-eligible.
Relevant SIC codes include 35110 (production of electricity), 35140 (trade of electricity), 72190 (other R&D on natural sciences), and 29100/29200 for hydrogen vehicle systems. The SIC code does not determine eligibility.
What Qualifies as R&D in Hydrogen and Energy Storage
Electrolyser Development (Green Hydrogen)
Proton exchange membrane (PEM), alkaline, and solid oxide electrolyser (SOEC) development are strong qualifying areas. Qualifying work includes: developing novel catalyst materials (typically iridium, platinum, or non-precious metal alternatives) with improved activity and durability under operation; engineering membrane electrode assemblies (MEAs) for improved proton conductivity, gas crossover, and mechanical integrity at high current densities; developing novel bipolar plate geometries, coatings, and flow-field designs for improved mass transport and reduced ohmic losses; designing stack assembly processes that achieve required tolerances without degrading membrane performance; and building control systems that optimise electrolyser operation across varying renewable energy input profiles where standard PID control was insufficient.
Fuel Cell Development
Fuel cell development follows a similar pattern. Qualifying work includes: novel catalyst layer development for improved durability under wet-dry cycling; membrane durability improvements for automotive or stationary power applications; advanced thermal and water management systems where standard approaches were insufficient for the duty cycle; and novel cell designs for high-temperature PEM or SOFC applications where the materials science at operating temperature introduced genuine uncertainty.
Battery and Grid-Scale Energy Storage
Beyond lithium-ion, novel battery chemistries (sodium-ion, flow batteries, lithium-sulfur, solid-state) all involve genuine technical uncertainty and produce strong claims. Even within lithium-ion, qualifying work includes: novel anode or cathode material development; electrolyte formulation for improved low-temperature or high-voltage performance; novel cell formats (pouch, prismatic) requiring experimental determination of electrode stacking, welding, and electrolyte filling processes; thermal management systems for high-power or high-capacity packs; and battery management system (BMS) algorithms for novel state-of-health estimation, second-life assessment, or fast-charging without degradation.
Hydrogen Storage and Distribution
Physical hydrogen storage (compressed gas, liquid, cryo-compressed) and material-based storage (metal hydrides, chemical hydrogen carriers, ammonia) all generate qualifying R&D where the materials science or engineering was genuinely uncertain. Pipeline hydrogen blending studies involving novel materials qualification, compressor seal development, and integrity monitoring systems may also qualify.
Digital Systems and Predictive Modelling
Digital twin development for electrolyser degradation modelling, grid-integration algorithms that dispatch storage assets across multiple frequency response and capacity market products simultaneously, and novel ML-based state-of-health models all qualify where the technical approach required experimental development. Software embedded in energy management systems is assessed on the same BIS Guidelines test as any other software.
What Does NOT Qualify: Hydrogen and Storage Anti-Patterns
These are the most common non-qualifying items in hydrogen and storage claims:
- Deploying commercially available electrolysers without modification. Purchasing a PEM electrolyser from an established vendor, installing it, and operating it per specification is a capital project, not R&D. The R&D is in the development of the electrolyser or its control system.
- Safety compliance and ATEX certification. Developing a safety case, obtaining ATEX certification, and conducting DSEAR risk assessments are not R&D, even though they are technically demanding. The engineering work that preceded the safety case may qualify.
- Planning and permitting activity. Environmental impact assessments, grid connection applications, and planning consent processes are not R&D.
- Site construction and civil engineering. Constructing a hydrogen production facility or battery storage site is capital expenditure. R&D allowances under CAA 2001 may apply to some capital R&D assets, but the construction itself is not qualifying R&D expenditure.
- Standard power electronics integration. Wiring commercially available inverters, converters, and grid meters to a storage system per published specifications is not R&D.
Qualifying Costs for Hydrogen and Storage Companies
Staffing costs. Electrochemists, materials scientists, chemical engineers, electrical engineers, mechanical engineers, and software engineers directly engaged in qualifying R&D. Safety engineers and project managers are typically excluded unless they contribute directly to the technical resolution of uncertainty.
Consumables and materials. Precious metal catalysts, membrane materials, electrolyte chemicals, cell components, and other materials consumed in qualifying bench and pilot-scale work. This is often the largest single cost item in a hydrogen or battery chemistry claim and must be distinguished from materials used in commercial production or demonstration projects.
Subcontractors. UK-based research partners, specialist electrochemical test labs, and university groups engaged on qualifying work are claimable at 65% for unconnected parties. Overseas partners are excluded under the merged scheme's UK-only rule.
Cloud and software costs. Computational chemistry software, electrochemical simulation licences, and cloud compute for digital twin training or degradation modelling are claimable where directly used in qualifying R&D. See the qualifying expenditure guide for full details. The glossary covers the key scheme terms.
ERIS for Hydrogen and Storage Companies
The majority of early-stage hydrogen and storage companies are pre-revenue or early-revenue. Where qualifying R&D expenditure exceeds 30% of total expenditure and the company is loss-making, ERIS at 27% applies. For a company spending £1.5m on qualifying R&D out of £3.8m total (intensity 39%), ERIS returns £405,000 versus £300,000 under the standard merged scheme. That difference is material for a capital-intensive deeptech business managing a limited runway.
Worked Example: A Green Hydrogen Electrolyser Company
A UK green hydrogen company (SIC 72190), pre-revenue, has total expenditure of £3.2m for the year to 31 March 2026. It employs 12 electrochemists and materials scientists, 8 mechanical and electrical engineers, and 5 software engineers. It has also received a £600,000 Innovate UK grant for a specific catalyst development project. A specialist review identifies:
- £820,000: qualifying staff costs at 70-100% R&D apportionment, excluding any staff costs funded by the grant.
- £230,000: catalyst materials, membrane components, and stack hardware consumed in qualifying bench and pilot trials, excluding grant-funded items.
- £65,000: UK university subcontract for electrochemical characterisation (65% of £100k invoiced).
- £50,000: computational chemistry software and cloud compute for modelling work.
Total qualifying spend (non-grant-funded): £1,165,000. R&D intensity: £1,165k / £3.2m = 36.4%. Company is loss-making and above the 30% ERIS threshold.
Credit under ERIS: £1,165,000 x 27% = £314,550 payable as cash. Under the standard merged scheme at 20%: £233,000. ERIS adds £81,550.
HMRC Enquiry Risks for Hydrogen and Storage Companies
HMRC's main concerns in this sector are: grant-funded expenditure included in the R&D claim without proper removal of subsidised costs; consumable claims that include materials used in demonstration or pilot-project delivery rather than purely in R&D trials; capital expenditure on pilot plant or test rigs presented as R&D consumable cost; and ERIS intensity calculations where total expenditure has been narrowed by excluding capital spend. An experienced adviser will ensure the grant-cost split is clean, distinguish bench R&D from demonstration activity, and build the ERIS intensity calculation on total company expenditure as HMRC defines it.
What to Do Next
If your hydrogen or storage company employs scientists and engineers resolving genuine technical challenges, the claim is worth assessing. The eligibility checker takes five minutes. For a full review, request a free assessment. Related guides: CleanTech R&D tax credits, Engineering R&D tax credits, merged scheme overview, and qualifying expenditure categories.