Tax advisers have less than one month to register under new requirements

HMRC is warning tax advisers that they have less than one month to register under new mandatory requirements that come into force in August.

The first phase of Modernising and Mandating Tax Adviser Registration (MMTAR) closes on 18 August 2026 for new tax advisers, or advisers interacting with HMRC without an agent services account (ASA), Self Assessment or Corporation Tax account. The changes are designed to raise standards in the tax advice market and protect taxpayers.

MMTAR is a single, streamlined digital registration system that is replacing a range of previous processes, making it easier for tax advisers to interact with HMRC.

Registration is free and online. Step-by-step guidance and an interactive checker tool are available on GOV.UK to help advisers understand if they need to register and what action they must take.

Failing to register could delay or disrupt services for clients, and may see tax advisers face restrictions on their ability to interact with HMRC on clients’ behalf. Where advisers continue acting without registering when instructed to stop, HMRC may apply sanctions including financial penalties.

Robert Jones, HMRC’s Director of Intermediaries, said:

“These new requirements will help create a fairer, more transparent tax advice market, support those advisers who meet high standards, and give taxpayers greater confidence in the advice they receive.

“And with one month to go until the first registration deadline, tax advisers who have not yet registered should act now and check the guidance on GOV.UK.”