How Far Back Can I Claim R&D Tax Credits?


HMRC allows you to apply for R&D Tax Credits up to two years after the end of the accounting period in which your R&D took place. You can do this even if you’ve already filed your corporate tax return.

The R&D Tax Credits scheme is a government benefit that promotes UK innovation by offering tax relief to companies who’ve performed qualifying research and development. You usually apply for tax credits along with your yearly tax return. But HMRC allows companies to apply for tax credits retrospectively – up to two years after the end of the financial year in which the R&D occurred. That gives you plenty of time to submit your application.


Let’s say you conducted qualifying R&D between January and July in 2017, and that your financial year ended September 1st. Your application deadline would be September 1st, 2019.

What if I’ve already filed?

It doesn’t matter if you’ve already filed your tax return for the period in question. As long as you’re within two years of the end of the period, you can simply amend your return. In fact, we actually recommend companies apply for R&D Tax Credits via amending their CT600 in their original tax return. This nifty shortcut speeds up HMRC’s processing times by rerouting your filing straight to an HMRC R&D specialist who understands your application.

How much can I claim?

If you’re an SME – which for tax purposes is determined by your turnover, staff headcount and balance sheet – you can claim between 15% and 33% of your R&D costs via the SME scheme. You can do this even if your R&D failed. If you’re a large company, you qualify for the RDEC scheme, which lets you claim 12% of your R&D costs back as tax credits. 

When will I get my tax credits?

HMRC aims to process R&D Tax Credits claims within 28 days. In our experience though, it can take up to 90 days for HMRC to process a claim and a further 10 to transfer the money. If you want your money sooner, check out our Advance Funding service.

Get in touch

If you have any questions about your claim, whether you qualify, or R&D Tax Credits generally, feel free to give us a call on 020 7748 8999 or send us an email. Our team of tax credits experts would be happy to help.

If you are curious about R&D Tax Credits, Innovation Grants and Open Culture