Compliance

Compliance Trends: Mandatory Tax Adviser Registration in the UK from May 2026

UK tax advisers must now register with HMRC under the new MMTAR regime—what this means for compliance, timelines, and avoiding penalties.

By NomadicTax Research Team • 5-8 min read • June 5, 2026

## What Is MMTAR: Modernising and Mandating Tax Adviser Registration Starting **18 May 2026**, the UK has rolled out a new mandatory registration requirement for tax advisers who are **paid to interact with HMRC on behalf of clients**. This initiative is part of the MMTAR scheme, aiming to simplify processes and enhance quality and accountability in advisory services. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) Build-on earlier consultations and policy work linked to Budget 2025, the scheme launches in phases—different adviser groups register between **May 2026 and March 2027**. ([gov.uk](https://www.gov.uk/government/publications/mandatory-tax-adviser-registration-with-hmrc?utm_source=openai)) --- ## Key Obligations Under the New Rules * **Who must register**: Anyone getting paid to deal with HMRC on someone’s tax affairs—includes overseas advisers interacting on behalf of UK clients. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) * **Digital registration via an Agent Services Account (ASA)** is required; certain identity and business info will be requested. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) * **Phased windows** of registration: * 18 May–18 August 2026: New advisers, or those without an ASA or Self Assessment/Corporation Tax account. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) * 18 August–18 November 2026: Advisers with SA or CT accounts but no ASA. * 18 November 2026–18 February 2027: Payroll‐only advisers. * 31 Dec 2026–31 Mar 2027: Final wrap-up window. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) * **Exemptions apply**, e.g. voluntary sector or organisations not receiving payment; or those not interacting with HMRC. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) --- ## Risks of Non-Compliance * Advisers operating without registration may face risk of penalties or inability to offer services or interact with HMRC for clients. * Clients may suffer service delays or be exposed to untrained advisers. The lack of clear professional standards could lead to reputational and legal risk. --- ## How Tax Advisers Should Prepare 1. Check whether you **must register**: review if you’re paid, interact with HMRC, or act via agent services. 2. Set up an **Agent Services Account (ASA)**, if you don’t have one. 3. Gather identification and business credentials: UTR, company registration, VAT number, National Insurance number, etc. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) 4. Engage with clients and other advisers early—understand whether you’re exempt. 5. Stay informed when your registration window opens. Missed windows may delay compliant operations. --- ## Example Compliance Timeline * Alice begins paid advisory work in agency interactions with HMRC on 1 June 2026—she has no ASA. She must register in the **first window** (18 May–18 August), the window applicable to her group. * * Bob offers payroll services only—his window opens 18 November 2026. * Carla already has an ASA and SA account—window for her group opens 18 August 2026. --- ## Action Checklist - Determine adviser group and applicable registration window. - Create or confirm ASA. - Collect documents (UTR, registration info, IDs). - Monitor HMRC communications for guidance or changes. - Ensure compliance with professional and ethical standards.