HMRC announced on 18 August 2026 that the second phase of mandatory tax adviser registration had opened, requiring eligible advisers to register by 18 November 2026. The phase covers advisers with Self Assessment or Corporation Tax accounts who do not have an agent services account (ASA), according to the tax authority.

HMRC said advisers who solely provide professional payroll services do not need to register before 18 November, while financial services organisations do not need to register before 31 December 2026. Registration is free and online, and advisers who already hold an ASA do not need to register again; HMRC said they would be moved to the new digital service by 31 March 2027.

The department reported that more than 4,000 applications were submitted and over 2,000 accounts created during the first registration window, which closed on 18 August 2026. Robert Jones, HMRC's Director of Intermediaries, said the measures were intended to reinforce trust and transparency and support high standards in the tax advice market. HMRC said advisers who submit an application can continue engaging with the department while it is processed, and that failure to register when required could lead to enforcement action, including financial penalties. The government is investing £36 million to modernise HMRC's tax adviser services.