New online service for uploading documents during HMRC compliance checks

HMRC has introduced a new online service that allows taxpayers and their authorised agents to upload documents and provide information electronically during a compliance check. 

The new service, launched on 3 August 2026, is available where HMRC's compliance team has issued a letter requesting additional information. Rather than responding by post, users can securely upload supporting documents through a dedicated online form, helping to streamline the exchange of information during an enquiry. 

To use the service, you will need the case reference number shown on HMRC's letter and must sign in with a Government Gateway account. Those without sign-in credentials can create them as part of the process. The service also allows users to save their progress and return later if they are unable to complete their submission in one session. 

Up to 10 files can be uploaded with each submission, with individual files limited to 15MB. A range of common file formats is accepted, including PDF, Word, Excel, OpenDocument and JPEG. Where more than 10 documents need to be provided, they should be submitted in separate batches. 

Once the information has been submitted, HMRC will issue a confirmation email containing a submission reference number. HMRC will then review the information and contact the taxpayer or their agent if any further details are required. 

The new service is expected to make it easier and quicker for taxpayers and agents to respond to information requests, reducing reliance on postal correspondence and supporting HMRC's wider move towards digital services during compliance checks. 

More information on the service can be found by following this link.