Compliance
HMRC’s New Mandatory Registration for Paid Tax Advisers: What Global Practitioners Need to Know
A sweeping UK reform requires any paid adviser who interacts with HMRC on behalf of a client to register under the Modernising and Mandating Tax Adviser Registration (MMTAR) scheme starting from May 18, 2026—key reading for advisers operating internationally.
By NomadicTax Research Team • 5-8 min read • June 18, 2026
## Overview of the MMTAR Reform
On **18 May 2026**, the UK introduced the **Modernising and Mandating Tax Adviser Registration (MMTAR)** requirement. Any tax adviser who is paid to deal with HMRC on behalf of a client must register for an Agent Services Account (ASA). This replaces many prior agent registration systems. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
The rollout will take place in stages:
- **18 May to 18 August 2026**: New advisers and those interacting with HMRC (without a Self Assessment or Corporation Tax account) must register. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
- **18 August to 18 November 2026**: Advisers who already have Self Assessment or Corporation Tax accounts will need to register. ([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 to 18 February 2027**: Advisers solely engaged in payroll services must register. ([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 to 31 March 2027**: Organisations with an existing ASA and financial services firms will be required to register. ([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 for Global Advisors
If your practice involves advising UK clients or interacting with HMRC, or you accept referrals from UK-based clients, the following will impact you:
- You must maintain an active UK **ASA registration** to lawfully offer paid tax advice in relation to UK tax affairs. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
- Foreign-based tax firms offering advice to UK-resident clients are also caught by this requirement. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
## Action Points for Compliance
1. **Determine your status**: Are you a paid adviser dealing directly with HMRC? If yes, registration is necessary. If you're offering free advice, or certain volunteering services, there may be exemptions. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
2. **Prepare requisite documents**: UTR, company registration, National Insurance, etc., depending on entity type. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
3. **Plan for phased registration**: Register under your designated stage to avoid delays in client work. Missing your window may lead to administrative complications.
4. **Update clients**: Let UK-based clients know about this change—your prior practices might be invalid under new rules.
5. **Maintain records of compliance**: HMRC may check whether your registration was active when reports or submissions were made.
## Example Scenario
Suppose you are a U.S.-based accountant advising a UK resident on Self Assessment. Even if no UK office is involved, because you're **paid to interact with HMRC**, you must register under ASA once that category is active for “foreign advisers.” Failure could result in non-recognition of your filings or disputes with HMRC.
**Summary:** Stay ahead of deadlines, confirm whether you need registration, get your ASA set up, and maintain compliance. If in doubt, consult a UK-qualified tax specialist or legal counsel.
By proactively engaging with the MMTAR regime, international advisers can safeguard reputational risk, avoid possible sanctions, and deliver certainty to UK clients.