The rate that applies to an R&D claim is fixed by the period the claim covers, not by the year you file it. This page collects every SME and RDEC rate from 2015 onwards alongside the current merged scheme and ERIS rates, so you can check a claim already filed, value a backdated one, or work out what a particular year was worth. The old schemes close to amendment in stages, year end by year end, with the last standard deadlines in late March 2027, which makes the historical figures a live question rather than an archive.
What are the R&D tax credit rates in 2026?
Two rates are in force for accounting periods beginning on or after 1 April 2024, and both continue to apply in 2026. The merged R&D expenditure credit pays a taxable credit of 20% of qualifying expenditure to companies of every size: 15p per £1 net at the 25% corporation tax main rate, 16.2p at 19% or for a loss-maker taking the credit in cash. ERIS pays loss-making SMEs whose R&D is at least 30% of total expenditure up to 26.97p per £1, tax free. A claim filed in 2026 for an earlier period uses that period’s rates, set out below.
The rates at a glance
| Period | SME additional deduction | SME payable credit rate | SME loss-maker cash per £1 | RDEC rate | RDEC net per £1 |
|---|---|---|---|---|---|
| 1 April 2015 to 31 December 2017 | 130% | 14.5% | 33.35p | 11% | 8.8p, then 8.91p from April 2017 |
| 1 January 2018 to 31 March 2020 | 130% | 14.5% | 33.35p | 12% | 9.72p |
| 1 April 2020 to 31 March 2023 | 130% | 14.5% | 33.35p | 13% | 10.53p |
| From 1 April 2023, old-scheme periods | 86% | 10%, or 14.5% if R&D-intensive | 18.6p, or up to 26.97p if R&D-intensive | 20% | 15p to 16.2p |
| Accounting periods beginning on or after 1 April 2024 | 86%, ERIS only | 14.5%, ERIS only | Up to 26.97p under ERIS | 20% merged credit | 15p to 16.2p |
The first four rows are set by the date the expenditure was incurred, so a single accounting period can straddle two sets of rates. The last row is set by the date the accounting period began, and in that row the final two columns are the merged scheme rather than RDEC. The distinction is explained immediately below. RDEC and merged scheme figures are net of corporation tax; the SME and ERIS credits are not taxable.
Which date decides the rate?
Two different date tests run through that table, and confusing them is the most common error we see in claims for older periods.
The April 2023 rate changes follow the date the expenditure was incurred. A company with a 31 December 2023 year end spent three months of that year under the 130% deduction and nine months under 86%, and the claim has to be split accordingly. The same applies to RDEC moving from 13% to 20%.
The merged scheme and ERIS switch follows the date the accounting period began. There is no splitting here. A 12-month period that began on 1 March 2024 sits entirely under the old schemes, even though almost all of it falls after 1 April 2024. Our guide to which R&D scheme applies to your company works through the test by date.
April 2015 to March 2020: 130% SME relief, RDEC at 11% then 12%
The SME rates did not move at all in this window. Qualifying expenditure attracted an additional deduction of 130%, giving a total deduction of 230%, and a loss-making company could surrender the resulting loss for a payable credit at 14.5%: 33.35p per £1 of qualifying spend. A profitable SME saved 24.7p per £1 at the 19% corporation tax rate that applied from April 2017.
RDEC moved twice. The credit was 11% of qualifying expenditure for expenditure incurred from 1 April 2015, rising to 12% from 1 January 2018. Because RDEC is taxable, the net benefit is lower than the headline suggests: 8.8p per £1 while corporation tax stood at 20%, 8.91p once the rate fell to 19% in April 2017, and 9.72p at the 12% rate.
April 2020 to March 2023: RDEC rises to 13%
The SME rates were unchanged again: 130% additional deduction, 14.5% surrender rate, 33.35p per £1 in cash for a loss-maker surrendering in full, 24.7p per £1 of tax saved for a profitable company at 19%. RDEC rose to 13% for expenditure incurred from 1 April 2020, worth 10.53p per £1 after corporation tax at 19%.
On £100,000 of qualifying expenditure incurred in this window:
- Loss-making SME, surrendering in full. £100,000 x 230% = £230,000 of deduction, surrendered at 14.5%: £33,350 in cash.
- Profitable SME. An additional deduction of £130,000, worth £24,700 at the 19% corporation tax rate.
- Company claiming RDEC. A £13,000 credit, taxable at 19%, worth £10,530 net.
One change in this window affected value rather than rate. For accounting periods beginning on or after 1 April 2021, the payable SME credit is capped at £20,000 plus 300% of the company’s relevant PAYE and National Insurance contributions, which bites on loss-makers with a small UK payroll and a large subcontracted R&D budget.
From April 2023: SME rates fall, RDEC jumps to 20%
For expenditure incurred on or after 1 April 2023, the SME additional deduction fell from 130% to 86% and the surrender rate from 14.5% to 10%. A loss-making SME surrendering in full received 18.6p per £1 instead of 33.35p, a little over half the old rate.
Loss-making SMEs that were R&D-intensive kept the 14.5% rate, worth up to 26.97p per £1 alongside the 186% total deduction. The intensity threshold was relevant R&D expenditure of at least 40% of total relevant expenditure when it was introduced, and it was reduced to 30% for accounting periods beginning on or after 1 April 2024 under Enhanced R&D Intensive Support (ERIS).
For profitable SMEs, corporation tax moved at the same time as the deduction. From April 2023 the main rate is 25%, the small profits rate is 19% and marginal relief applies between them, so the 86% deduction is worth up to 21.5p per £1 at the main rate and less further down.
RDEC went the other way, from 13% to 20% for expenditure incurred from 1 April 2023: 15p per £1 net at the 25% main rate, 16.2p at 19%.
Accounting periods beginning on or after April 2024: the merged scheme and ERIS
The SME and RDEC schemes were replaced for accounting periods beginning on or after 1 April 2024. Most companies now claim the merged R&D expenditure credit: a taxable credit of 20% of qualifying expenditure, worth 15p per £1 after corporation tax at the 25% main rate and 16.2p at 19%. Loss-makers receive 16.2p in cash: with no profits chargeable at the main rate, the notional tax deducted from their credit is applied at the 19% small profits rate rather than 25%, whatever the company’s size — and the amount deducted is not lost, but carried forward against future corporation tax or available to surrender within a group.
Loss-making SMEs whose relevant R&D expenditure is at least 30% of total relevant expenditure claim ERIS instead: an 86% additional deduction and a 14.5% payable credit, worth up to 26.97p per £1, and the ERIS credit is not taxable.
On £100,000 of qualifying expenditure:
- Merged scheme, profitable at the 25% main rate. A £20,000 credit, taxed at 25%: £15,000 net.
- Merged scheme, loss-making. A £20,000 credit less notional tax at 19%: £16,200 in cash.
- ERIS. £100,000 x 186% x 14.5% = £26,970 in cash, assuming sufficient losses.
The cap of £20,000 plus 300% of relevant PAYE and NIC applies to payable credits under both current schemes.
When the rules changed
Rates are only half the history. The compliance regime tightened over the same period, and for older periods the administrative dates decide whether a claim can be made at all.
- Accounting periods beginning on or after 1 April 2021. The SME payable credit cap arrives: £20,000 plus 300% of relevant PAYE and NIC.
- Accounting periods beginning on or after 1 April 2023. The claim notification requirement applies. First-time claimants, and companies that have not claimed in the previous three years, must notify HMRC within six months of the end of the period of account. There is no late route.
- Claims filed from 8 August 2023. The Additional Information Form is mandatory for every claim, amendments included.
- Accounting periods beginning on or after 1 April 2024. The merged scheme and ERIS replace the SME and RDEC schemes. Overseas subcontractor and externally provided worker costs are restricted, and new contracted-out rules decide which party claims.
- Late March 2027. The last standard claim deadlines for old-scheme periods with twelve-month periods of account; the window runs two years from the end of the period of account, so long periods of account can reach later into 2027, and many earlier year ends have already closed.
Which rules apply to my claim?
Start with the date your accounting period began, because that decides whether the period sits under the merged scheme and ERIS or the old SME and RDEC schemes. Which R&D scheme applies to your company settles it. Then look at the dates of the expenditure itself: an old-scheme period straddling 1 April 2023 uses two sets of rates in the same claim.
For a working figure on your own numbers under the current schemes, use the claim value calculator. For a period already filed, the question is not only what it is worth but whether it can still be claimed: backdated R&D claims and the 2027 deadlines covers the claim windows and the notification rule, which closes more backdated claims than the deadline itself does.
Talk it through with a chartered adviser
Rates are the straightforward part of an R&D claim. Whether the expenditure qualifies, which scheme the period falls under and whether the claim stands up to scrutiny are the questions that decide what a company actually receives, and HMRC checked around one in six claims in 2023-24, its latest published figure. LimestoneGrey is a firm of chartered tax advisers and chartered accountants specialising in R&D tax relief regulated by ICAEW, every claim is signed off by a chartered adviser, and enquiry support is included as standard.
If you want a view on what a particular year is worth, or whether an older period can still be claimed, get in touch. For the wider picture, start with our R&D tax relief guide.
Written by Matthew Jones ACA CTA. Last reviewed July 2026.
Sources
- Work out your R&D tax relief — the historical SME and RDEC rates.
- R&D relief for SMEs — the SME rates of 86% / 10% / 14.5% from April 2023.
- CIRD89710: RDEC rate — the RDEC rate rising from 13% to 20%.
- Merged scheme & ERIS guidance — the 20% merged credit, ERIS at 186% and 14.5%, the 30% intensity test and the PAYE cap.
- Corporation Tax rates and allowances — the corporation tax rates behind the net figures.
- Tell HMRC you plan to claim — the six-month claim notification window.
- Additional information form guidance — the AIF, mandatory for every claim since 8 August 2023.
- FA 1998 Sch 18 para 83E and CIRD81800 — the claim time limit (two years from the end of the period of account) behind the 2027 deadlines.