Registration is now open for tax advisers in the second phase of the new Modernising and Mandating Tax Adviser Registration (MMTAR) rollout.
This applies to any advisers with Self Assessment or Corporation Tax accounts, but without an agent services account (ASA). They have until 18 November 2026 to register.
HM Revenue and Customs (HMRC) is encouraging advisers in the second registration window to check if they need to register and submit their application as soon as possible.
More than 4,000 applications were submitted and over 2,000 accounts created during the first registration window, which targeted the smallest agent audience group.
These mandatory changes are designed to raise standards in the tax advice market, protect taxpayers, and support those who play by the rules.
MMTAR is a single, streamlined digital registration system that replaces 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 they need to do. Eligible tax advisers must meet HMRC’s registration conditions to apply for an ASA.
Robert Jones, HMRC’s Director of Intermediaries, said:
“Together, these measures will reinforce trust and transparency across the tax advice market, supporting high standards and helping taxpayers access advice with greater confidence.
“Now that the second registration phase is open, advisers in the next group should check the guidance on GOV.UK and make sure they register by 18 November 2026.”
Registering on time will help advisers to continue supporting their clients without disruption and maintain the trust that individuals and businesses place in professional tax services.
Advisers who missed the first registration window or who are new entrants to the tax advice market should register as soon as possible. Advisers who submit an application and receive a registration number can still continue to engage with HMRC while their registration is being processed. Access to HMRC’s online services will not be affected in the short term.
HMRC may limit an adviser’s ability to act on behalf of clients if they fail to register when required. Advisers who continue to operate without completing the registration requirement could also face enforcement action, including financial penalties.
