Family one: eligibility errors
The project never met the definition. The recurring shapes come straight from HMRC’s own examples. Adapting existing methods in a routine way: its website-modernisation example concludes exactly that. Goals that are commercial rather than technological: its market-research analytics example fails because the field itself does not qualify. Cosmetic and aesthetic work: the guidelines exclude it in terms. And “we did not know how” that dissolves once a competent professional’s knowledge is applied: the readily-deducible test.
The fix is brutal honesty at step zero, with the right professional making the call. That conversation lives on what counts as R&D and, for the no-claim outcome, when you do not qualify.
Family two: boundary errors
Real R&D, overclaimed. The project qualified, and then the claim swept in the requirements phase, the routine build, the rollout, the training and the year of fine-tuning. The guidelines fix the window: R&D starts when work on the uncertainty starts, and ends when it is resolved or abandoned. HMRC’s examples enforce it to the day. In its trial-programme example, uncertainty resolves on day 12 and the remaining 8 days of refinement do not qualify.
The fix is drawing the boundary explicitly in the narrative, sub-project by sub-project, before costing anything: method on the technical narrative.
Family three: costing errors
The work qualified, the boundary was right, the money was wrong. The regulars:
- whole-company or round-number staff apportionments with no evidence behind them
- the 65% restrictions on unconnected subcontractors and agency workers missed
- overseas contractor work claimed as if the restrictions had not happened
- consumables that ended up in sold products
- capital spend and excluded categories (rent, rates, patents) smuggled in
- numbers that do not reconcile to the accounts
The fix is mechanical discipline against the category pages, starting at qualifying costs.
Family four: process errors
The claim was right and died anyway. A missed claim notification window makes the claim invalid before any technical question arises. A return filed before the Additional Information Form gets the claim rejected. And the two-year claim limit waits for nobody. These are calendar problems, and calendars are the one part of tax that forgives nothing.
- HMRC, GfC3 (Help to see if your work qualifies as R&D), Parts 3 to 5, gov.uk
- DSIT, Meaning of research and development for tax purposes: guidelines (2023), gov.uk
- HMRC, Check what Research and Development (R&D) costs you can claim, gov.uk
- HMRC, Approach to Research and Development tax reliefs 2023 to 2024, gov.uk
Frequently asked questions
What is the single most common error?
Claiming the whole commercial project. HMRC's guidance repeatedly separates the qualifying sub-project, the uncertainty window, from the surrounding delivery work, and claims that ignore that boundary overstate everything downstream: activities, time, costs.
Are cost errors or eligibility errors worse?
Eligibility errors are usually bigger, because they take the whole project with them. Cost errors are more frequent. Enquiries commonly find both, since a project claimed without a boundary produces costs without a basis.
We found an error in a filed claim. Now what?
Correct it, on your initiative, quickly. Amendment within the time limit, or HMRC's disclosure facility beyond it, with penalties scaling heavily in favour of unprompted correction. The worst option is knowing and waiting.
Do honest mistakes get penalised?
A mistake made despite reasonable care carries no penalty, though the tax corrects with interest. Carelessness does, and the difference is usually evidenced by process: what you checked, what advice you took, what records existed at the time.