HMRC Tax Adviser Registration Rules 2026 Explained

The UK's HMRC released a public notice informing that it is introducing a new mandatory registration system for tax advisers who are paid to deal with HMRC on behalf of clients. While the measure came into effect on May 18, 2026, the registration process will be introduced gradually. The introduction of registration requirements is part of the Modernising and Mandating Tax Adviser Registration (MMTAR) programme announced at Budget 2025 and published in February 2026.

Registration Requirements and Implementation Timeline

The registration requirements apply to tax advisers who are paid to communicate or interact with HMRC on behalf of the clients. When registering for an agent services account with HMRC, a business must satisfy specific eligibility conditions, as well as certain eligibility conditions for certain individuals connected to the business, referred to as “relevant individuals.”

Thus, for businesses with five officers or fewer, all officers will automatically be treated as relevant individuals, regardless of whether they are directly involved in providing tax services. As a result, the business must report details for every officer. If a business has six or more officers, it must first identify those who are actually responsible for strategic or management decisions related to tax advisory activities, rather than automatically including every officer.

As noted, the new registration system will be introduced in several phases, with different categories of tax advisers required to register during specific time periods. The first phase started on May 18 and ends on August 18, 2026. During this phase, new tax advisers and advisers who interact with HMRC without holding an Agent Services Account (ASA), Self Assessment account, or Corporation Tax account must register.

The second phase is scheduled for August 18 to November 18, 2026, during which advisers who already have a Self Assessment or Corporation Tax account but do not yet have an ASA must complete the registration process. During the third phase, between November 18, 2026, and February 18, 2027, advisers that exclusively provide payroll services must register.

Finally, from December 31, 2026, to March 31, 2027, advisers who already hold an ASA, as well as financial services organizations, will be brought into the regime. Notably, a full definition of financial services organizations will be set out later in secondary legislation.

Conclusion

The HMRC clarified that if a person is paid to deal with someone else’s tax affairs by interacting with HMRC, they are treated as a “tax adviser” and will generally be required to register for an Agent Services Account (ASA), unless they fall within a specific exemption. Therefore, all businesses and individuals, including foreign ones, acting in this way should examine whether exemptions apply to them or whether they must register with HMRC.

Source: HM Revenue & Customs