Yes. R&D tax relief rewards the attempt to resolve scientific or technological uncertainty, not the outcome. A project that never reached a working result can still qualify in full, and the legislation has always worked this way: the test is whether the work sought an advance through resolving uncertainty that a competent professional could not readily resolve, not whether the advance was achieved.
Why failure can strengthen a claim
Failed iterations are often the clearest evidence that the uncertainty was genuine. If a competent professional could have resolved the problem readily, the work would not have failed. A prototype that missed its performance target, a process that could not be scaled, an approach abandoned after months of testing: each one demonstrates that the answer was not deducible from existing knowledge, which is precisely what HMRC needs to see. In practice, we find the abandoned branches of a project are frequently easier to defend than the branch that eventually worked, because nobody can argue the solution was obvious.
The same logic applies within successful projects. Most R&D that ends in a working product passes through failed attempts on the way, and those attempts are part of the qualifying activity. Leaving them out of a claim both understates the qualifying work and weakens the story of uncertainty the claim depends on.
What you need to be able to show
The relief attaches to the attempt, but the attempt has to be evidenced. The Guidelines put it directly: even where the advance sought is not achieved or fully realised, the R&D still takes place — what matters is being able to describe what was attempted, why existing knowledge was insufficient, what was tried, and what was learned, including from the failures. The Additional Information Form requires a project description covering exactly this ground, and HMRC checked around one in six claims in 2023-24, its latest published figure, so the description needs to hold up under questioning.
Records do not need a statutory format. For a first claim, HMRC accepts that detailed contemporaneous records may not exist and justified estimates are acceptable; from then on, keep project documents, test results and staff time records as you go, because evidence created at the time the work was done is far more persuasive than reconstruction after the event.
One boundary worth stating plainly: a commercial failure is not the same thing as a qualifying project. A product that failed in the market qualifies only if the underlying work met the statutory definition, and a technical failure qualifies only if the problem was a genuine scientific or technological uncertainty rather than routine difficulty. Our guide to what counts as qualifying R&D sets out where that line falls.
Where to go next
If you shelved a project and assumed the spend was lost, it may still be claimable: the window for amending a return generally runs two years from the end of the accounting period. We will tell you honestly whether the work qualifies before any claim is prepared.
Written by Matthew Jones ACA CTA. Last reviewed July 2026.
Sources
- Guidelines on the meaning of R&D for tax purposes — paragraph 10: R&D still takes place even where the advance sought is not achieved.
- Check if a project qualifies as R&D for tax purposes — the definition the outcome does not change.
This page describes the rules as they stood at the review date above, as general information rather than advice on your circumstances. For how that distinction works, see our terms; for an answer on your own facts, talk to us.