HMRC has announced that registration is now open for the second phase of the Modernising and Mandating Tax Adviser Registration (MMTAR) rollout. The tax authority said on Tuesday that this phase applies to advisers with Self Assessment or Corporation Tax accounts who do not yet have an agent services account (ASA).
Deadline and Registration Window
Advisers in this group have until November 18, 2026, to register. HMRC said the registration window is open for three months and encouraged eligible advisers to check if they need to register and submit their application as soon as possible.
During the first registration window, which targeted the smallest agent audience group, more than 4,000 applications were submitted and more than 2,000 accounts were created.
Purpose and Benefits of MMTAR
HMRC said: "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.
Official Statement and Consequences
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 November 18, 2026."
HMRC stressed that advisers who missed the first registration window or 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 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. However, HMRC might 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.
