For accounting periods which began on or after 1 April 2023; Companies that have not previously claimed R & D or have not made a claim in the last three accounting periods need to notify HMRC that they intend to make a claim within six months of the end of the accounting period they wish to claim for.
So, a company with a 12 month accounting period ending on 31 March 2024 will need to notify HMRC by 30 September 2024. We will be reminding you as we approach deadlines.