What's new
The restriction is narrower than "no overseas costs", but it's real
Before this reform, where overseas R&D activity happened didn't generally affect whether the cost qualified. For accounting periods beginning on or after 1 April 2024, that changed for two specific cost categories: payments for contracted-out R&D, and payments for externally provided workers (EPWs, typically agency staff). Where the R&D activity itself takes place outside the UK, those costs generally no longer qualify, subject to a narrow exception (see gov.uk, "Check what R&D costs you can claim", and HMRC manual CIRD151000). For EPWs specifically, there's a separate route in as well: earnings that go through UK PAYE and Class 1 National Insurance still qualify regardless of where the work happens.
Worth knowing first: your own UK-payroll staff aren't affected by any of this. The restriction is about payments to contractors and externally provided workers, not your employees' salaries. A UK employee who travels abroad for genuine R&D work is still a normal staff cost, claimed as before.
The exception
Three things all have to be true, and it's fact-specific, not a checklist
Under CTA09/S1138A(2), overseas contracted-out or EPW costs can still qualify where all three of these hold: the conditions necessary for that R&D aren't present in the UK, those conditions do exist where the work actually happens, and it would be wholly unreasonable to expect the company to replicate them in the UK. HMRC's own manual describes the categories of "necessary conditions" as fairly wide, and deliberately doesn't reduce them to a fixed list. Broadly, they fall into two groups (CIRD151000):
- Geographical, environmental or social conditions: things that physically or naturally can't be replicated in the UK. Examples are disease prevalence or specific patient populations for a clinical trial, particular animal or plant distributions, deep-sea, desert or high-altitude environments, access to a specific geological feature, or a concentration of specialist expertise (a particular university research group, say) that genuinely doesn't exist here.
- Legal or regulatory requirements: where a law, regulator or accreditation body genuinely requires the activity to happen in a specific place, or requires a process that can only be satisfied there.
What HMRC says explicitly doesn't count: lower labour or overhead costs overseas, easier access to contractors or facilities abroad, and the general availability of skills or experience outside the UK. HMRC's own guidance is direct about this: had the primary reason for the overseas location simply been lower cost, that wouldn't satisfy the test. A genuinely cheaper overseas team is a real commercial reason to use them, but it isn't a reason the restriction is written to accommodate.
Worked example, from HMRC's own guidance
Same trial, two locations, two different answers
HMRC's manual gives a pharmaceutical example that shows the distinction well: a company runs part of a clinical trial in Germany because German regulators require in-country trial data before they'll grant local price reimbursement approval. That's a genuine legal and regulatory necessity: the trial can't be replicated in the UK and still satisfy the German approval process, so the overseas cost can qualify. Contrast that with a company running the same trial in a lower-cost jurisdiction purely because it's cheaper to recruit participants and staff there, with no regulatory requirement forcing the location. Same activity, different reason, different answer.
Decision helper
Alternatives and limitations
Whether the location genuinely satisfies the exception is a fact-specific judgement HMRC expects to be argued on the actual circumstances, not asserted. If overseas costs are a meaningful part of a claim, that's worth a proper review rather than a guess either way. This page doesn't cover who's entitled to claim contracted-out R&D in the first place. That's a separate question: see contracted-out R&D: who claims. And if you're not sure which scheme applies to the period in question, start with the scheme checker.