HMRC has introduced a new online service allowing taxpayers and authorised agents to upload documents or provide information directly as part of a compliance check. In this article, we explain what has changed for taxpayers and agents, and why care is still needed before responding to HMRC requests.

The new service, published on GOV.UK on 3 August 2026, is designed for taxpayers who have received a letter from HMRC’s compliance team asking for additional information. It allows users to submit documents through an online form, rather than relying on post, email, or other ad hoc methods.

What has changed?

Taxpayers and authorised agents can now use the portal to upload documents or send information where HMRC has requested this as part of a compliance check. To use the service, the taxpayer will need the case reference number shown on HMRC’s letter and must sign in with Government Gateway details.

HMRC states that each file must be 15MB or less and that up to 10 documents can be uploaded at a time. If more than 10 documents need to be submitted, they must be split into separate batches.

A welcome step towards a more efficient process

Making it quicker and easier to submit documents to HMRC is a positive development. In many cases, it should reduce delays and provide a clearer record of what has been sent and when. Once a submission has been made, HMRC will issue a confirmation email containing a submission reference number.

Why taxpayers should still proceed with care

However, the convenience of the new system should not distract from the fact that a compliance check is still an investigation. The documents and information provided to HMRC can influence the direction and outcome of the check, including how HMRC assesses the taxpayer’s behaviour and any potential penalty position if errors are identified.

Care should always be taken when responding to HMRC information requests. This is particularly important for unrepresented taxpayers, who may now find it easier to upload documents directly without first considering whether the request is valid, whether the documents are relevant, or whether further explanation is needed.

Although HMRC is entitled to request documentation that is reasonably required to check the accuracy of a submitted return, requests should still be reviewed carefully. Providing information without sufficient context, or submitting more than HMRC has asked for, can prolong a compliance check and create unnecessary follow-up questions.

What should taxpayers do before responding?

Before uploading documents or information, taxpayers should take time to understand exactly what HMRC is asking for and why. Where there is any uncertainty, it is sensible to seek advice from a qualified tax investigations specialist before making a submission.

The new portal should make the administrative side of a compliance check more efficient. But the substance of the response remains just as important as before. Taxpayers should ensure that any documents supplied to HMRC are relevant, accurate, and supported by the right explanation.

How we can help

If you have received a compliance check letter from HMRC, our tax disputes and investigations specialists can help you understand what HMRC is asking for, review the information requested, and prepare an appropriate response.

To speak to a member of our team, please complete the form below and we will be in touch to discuss how we can help, in the strictest confidence.