Compliance

Mandatory Tax Adviser Registration: What Tax Agents Need to Know from May 2026

From 18 May 2026, all paid tax advisers interacting with HMRC must register under the MMTAR scheme—this article guides you through eligibility, deadlines and practical steps.

By NomadicTax Research Team • 5-8 min read • May 18, 2026

## Overview The UK Government has introduced a new regime called **Modernising and Mandating Tax Adviser Registration (MMTAR)**. From **18 May 2026**, tax advisers who are paid to interact with HM Revenue & Customs (HMRC) on behalf of clients must register using a single, digital service.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) MMTAR seeks to streamline a patchwork of registration routes, improve standards and protect taxpayers.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) Agent Services Accounts (ASA) will be central to this new system.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) ## Who Needs to Register You are required to register if you: - are paid to interact with HMRC on someone else’s tax affairs (via phone, email, post, forms etc.)([gov.uk](https://www.gov.uk/guidance/check-if-and-when-you-need-to-register-as-a-tax-adviser-with-hmrc?utm_source=openai)) - help clients with Self Assessment, Corporation Tax, or similar obligations, unless exempt.([gov.uk](https://www.gov.uk/guidance/check-if-and-when-you-need-to-register-as-a-tax-adviser-with-hmrc?utm_source=openai)) **Exemptions include**: - in-house tax teams handling only their employer’s tax affairs([gov.uk](https://www.gov.uk/guidance/check-if-and-when-you-need-to-register-as-a-tax-adviser-with-hmrc?utm_source=openai)) - unpaid charitable work or helping friends/family without charge([gov.uk](https://www.gov.uk/guidance/check-if-and-when-you-need-to-register-as-a-tax-adviser-with-hmrc?utm_source=openai)) - certain intermediaries, such as for Import One Stop Shop, and VAT or customs representatives under specific criteria([gov.uk](https://www.gov.uk/guidance/check-if-and-when-you-need-to-register-as-a-tax-adviser-with-hmrc?utm_source=openai)) ## When to Register & Transition Phases Registration opens **18 May 2026** for: new advisers, or those without an ASA, Self Assessment, or 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)) Later phases: - **18 August 2026**: Advisers who have Self Assessment or Corporation Tax account but no ASA([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) - **18 November 2026**: Advisers providing payroll-only services([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) - **31 December 2026–31 March 2027**: Financial services organisations and those already with ASAs([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) You’ll have **three months** from your registration window start date to apply and get compliant.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) During these periods, you may still act while waiting for registration acceptance.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) ## Registration Conditions To successfully register, you must meet certain conditions:([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) - Supervision under anti-money laundering (AML) rules (unless exempt)([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) - No outstanding tax returns or unpaid tax (unless on a payment plan)([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) - No unspent convictions for tax or fraud offences([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) Also, “relevant individuals” in your business (directors, officers, people managing tax-advice activities) must be declared.([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) Overseas advisers will need authenticated documents and translations where applicable.([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) ## Practical Steps for Compliance 1. **Check if you fall into scope** using the interactive tool or guidance on GOV.UK.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) 2. **Prepare your application**, gathering your UTR, company registration, identity documents etc.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) 3. If overseas, get documents notarised and translated.([gov.uk](https://www.gov.uk/guidance/check-if-you-meet-hmrcs-conditions-to-register-as-a-tax-adviser?utm_source=openai)) 4. Appoint a qualified professional body or AML supervisory body if required.([gov.uk](https://www.gov.uk/guidance/tax-agents-handbook/getting-started?utm_source=openai)) 5. Stay informed—record deadlines based on your adviser group. You’ll have three months from when your group’s registration opens.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) ## Consequences of Non-compliance Failing to register when required means you can no longer legally interact with HMRC on clients’ behalf.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) Penalties are possible, services may be disrupted, trust could be eroded.([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) ## Why This Matters (Case Example) Suppose you're a tax adviser based overseas, helping UK clients with their Corporation Tax filings. You receive payment for this work. Under MMTAR, you **must register** starting 18 May 2026. Without AML supervision, you cannot meet registration conditions. Non-registration could force your clients to find new advisers or lead HMRC to ban you from acting. Your clients may suffer delayed filings, additional penalties. ## Action Plan Checklist - Determine which registration phase applies to you. - Gather required documents now—don’t wait until the window opens. - Ensure AML supervision is in place if needed. - Advise clients of your ability to deliver services under the new rules. - Monitor GOV.UK announcements for further guidance and tools. **Bottom line**: From mid-May 2026, paid tax advisers must join the new digital registration system. Plan ahead, comply early, to avoid disruption.