Does the work qualify?
R&D for tax means a project that seeks an advance in science or technology by resolving scientific or technological uncertainty. Advances in the arts, humanities or social sciences, including economics, don’t count2. Only companies chargeable to UK Corporation Tax can claim2.
Which scheme
| Merged RDEC | ERIS | |
|---|---|---|
| Who | Most claimants, including profitable SMEs1 | Loss-making SMEs that are R&D intensive1 |
| Relief | Expenditure credit of 20% of qualifying costs1 | Extra deduction of 86%, 186% in total1 |
| Payable cash | Through the credit | Up to 14.5% of the surrenderable loss1 |
| Intensity test | None | Relevant R&D spend at least 30% of total spend, including connected companies’1 |
A company that qualifies for ERIS can choose the merged scheme instead, but can’t claim both on the same costs1.
Before the return: the claim notification
You must tell HMRC in advance if you’re claiming for the first time, or your last claim was made more than 3 years before the end of the claim notification period. That period ends 6 months after the end of the period of account. Miss it and “your R&D tax relief claim will be invalid”3. HMRC has said a claim notification won’t be needed for claims made on or after 1 April 20273.
Check your company’s dates and set a reminder
Search the Companies House register. Your company page shows its filing dates, what to file next and a reminder you can set.
Before the return: the additional information form
Every R&D claim needs an additional information form, for each accounting period4. It goes in before the CT600 or on the same day; “If the tax return is submitted before the additional information form, the claim will be rejected”, and HMRC removes the claim from the return4. Its period dates must match the CT600’s exactly4. It asks for the company’s details, the senior R&D contact and any agent, the costs, and descriptions of the projects: the field of science or technology, the baseline, the advance sought and the uncertainties4.
In the CT600
The return confirms both forms with a cross in box 656 (claim notification) and box 657 (additional information form)5. A merged-scheme claim shows the expenditure credit as taxable income and completes the CT600L supplementary page; an ERIS claim puts the extra deduction in the tax computation, with the CT600L if a payable credit is claimed5.
Time limit
For a period of account of 18 months or less, the claim must be made within 24 months of its last day5. A period of account longer than 12 months needs a separate claim for each accounting period inside it5.
Filing your return
Whether a project qualifies takes specialist judgement, so take advice if you’re unsure. Fileyear’s accounts and tax return files R&D claims with the CT600: the claim’s own questions, checks on the claim notification and additional information form dates, and the CT600L page.