Mandatory HMRC registration for paid tax advisers begins rolling out from May 2026
HM Revenue and Customs has begun rolling out a new mandatory registration system for tax advisers, warning that advisers who fail to comply could face sanctions and lose the ability to act for clients. The new framework, known as Modernising and Mandating Tax Adviser Registration (MMTAR), officially launches online from 18 May 2026 and will be introduced in stages through to March 2027.
Under the rules, anyone paid to interact with HMRC on behalf of clients regarding tax affairs will generally need to register for an agent services account (ASA), unless an exemption applies. The requirement applies to advisers operating both within the UK and overseas where they deal with UK taxpayers.
HMRC said the new digital registration system is designed to replace several existing processes with a single streamlined platform intended to reduce administrative burdens and improve standards across the tax advice market.
The reforms were first announced during Budget 2025 following consultation in 2024. HMRC said respondents broadly supported the introduction of mandatory registration, which aims to improve accountability and make advisers easier to identify.
Robert Jones, HMRC’s Director of Intermediaries, said advisers should review the guidance and prepare before their registration window opens. He said the measures are intended to raise standards, support economic growth and help close the tax gap. The rollout will take place in phases.
From 18 May to 18 August 2026, the requirement applies to new tax advisers and advisers interacting with HMRC without an ASA, Self Assessment or Corporation Tax account. Advisers who already hold Self Assessment or Corporation Tax accounts but no ASA will follow between August and November 2026.
Payroll-only advisers will be invited to register between November 2026 and February 2027, while advisers who already hold an ASA and financial services organisations will move to the system between December 2026 and March 2027.
HMRC confirmed that registration is free and that advisers will generally have three months from the start of their registration period to apply. During that period, and while HMRC considers applications, advisers can continue acting for clients.
The department warned that advisers who fail to register by the relevant deadline, or who fail to meet registration standards, will not be permitted to interact with HMRC on behalf of clients. Continued activity after being told to stop could result in financial penalties.
HMRC also cautioned that failure to comply could disrupt services for clients and damage trust between advisers and businesses relying on professional tax support. The government said it is investing £36 million into modernising tax adviser registration systems as part of wider plans to improve efficiency and strengthen oversight within the sector.