What Patent Box is, in one paragraph
An elective Corporation Tax regime applying a 10% effective rate to profits attributable to qualifying patents, UK and specified European grants, held or exclusively licensed by the company. The election deadline is two years after the end of the accounting period in which the relevant profits arose. The regime also carries a development condition: the company, or a group company, must have undertaken qualifying development for the patent. It is a real computation with real complexity, streaming profits, the nexus-based R&D fraction, and it rewards companies whose profits genuinely trace to their own innovation.
Why it belongs next to an R&D claim
The two regimes were built to chain. The development that supports an R&D claim is usually the same activity that satisfies Patent Box’s development condition. And the modern Patent Box computation is nexus-based: its R&D fraction is constructed from R&D expenditure using the R&D definitions, tying the 10% rate to where the development actually happened. HMRC’s manual adds the practical confirmation: expenditure does not need to have been included in an R&D claim to count in the R&D fraction.
The honest framing is sequential, not simultaneous: R&D relief pays during the spend years; Patent Box pays in the profit years, if you patent and elect. Companies with granted patents and UK-taxed product profits are the clear candidates; loss-makers and the patent-averse usually are not, yet.
The decision in three questions
- Do profits trace to a patentable invention you developed? No patent, or profits that come from services around the invention rather than the invention, and the regime has little to bite on.
- Does the arithmetic clear the admin? Fifteen points of rate on modest relevant profits can be worth less than the computation costs; on substantial product profits it compounds year after year.
- Is the election window still open? Two years after the period end, the same discipline as every deadline on this site: diarise it when the profits first arrive, not when someone remembers.
Where the answers point at the regime, the R&D claim file you have already built, project records, development history, cost analysis, is most of the evidence Patent Box needs. That reuse is the quiet efficiency of doing the spend side properly first.
Frequently asked questions
Does claiming R&D relief affect our Patent Box, or vice versa?
They operate together by design: the Patent Box calculation uses R&D definitions of qualifying expenditure in its R&D fraction, and HMRC's manual confirms R&D spend does not have to have been in an R&D claim to count there. Neither claim switches the other off.
Is the 10% rate automatic once we have a patent?
No. Patent Box requires an election, within two years after the end of the accounting period in which the relevant profits arose, and the regime applies only where the company or a group company undertook qualifying development for the patent. Holding a patent passively is not enough.
We rarely patent our software. Should we bother?
Often the honest answer is no, and not patenting is a legitimate commercial choice. But companies sitting on patentable, profit-generating inventions while paying 25% on those profits are leaving the second half of the incentive unused, and the 15-point rate gap funds a lot of patent attorney time.
Is Patent Box within your fixed-fee claim service?
It is a separate regime with separate computations, so it is scoped and priced separately, and we say so rather than bundling it invisibly. Where your numbers suggest it is worth exploring, we will tell you that too.