HMRC published draft guidance on the advance tax certainty service in December 2025. The guidance explains the circumstances in which a business can use the service, the process for using the service and how clearance will be given by HMRC. A key point to note is that the service is restricted to projects that are expected to result in at least £1 billion of qualifying expenditure in the UK over the lifetime of the project. 

The service will launch on 1 July 2026. However, HMRC has announced that it will accept expressions of interest from 1 June 2026. The business can make an expression of interest by contacting their HMRC customer compliance manager or by emailing the dedicated mailbox. HMRC’s guidance (section 3.2) sets out the information the business should provide when making an expression of interest.  

HMRC will then organise a meeting with the business before it submits its formal clearance request. Depending on the complexity of the case, HMRC aims to respond by granting or rejecting the application for clearance within 90 days of receiving the formal submission.