A notice of HMRC enquiry was served within the statutory time limit, the letter was properly posted, postal disruption prevented the operation of the deeming provision but the appellant had not proved non-receipt of the enquiry letter. 

On 24 May 2021, the appellant (AGN) submitted an amended corporation tax return to HM Revenue and Customs (HMRC) for the year ended 30 September 2020. The amended return stated that AGN spent £1.6m on research and development (R&D) and included a claim for an R&D credit of £304,951. In accordance with HMRC’s ‘process now, check later’ approach, on 21 October 2021 the sum of £304,951 was paid to AGN. On 15 July 2022, an HMRC officer drafted a letter opening an enquiry into the amendment, addressed to AGN’s registered office at 5 Chancery Lane, London; that premises was occupied by another firm, which provided services for a number of companies, including AGN. Having received