Overview
The UK government is introducing Modernising and Mandating Tax Adviser Registration (MMTAR). From 18 May 2026, new registration requirements roll out for tax-advisers who interact with HMRC for others and are paid for their services. It’s aimed at raising standards and increasing accountability. (gov.uk)
Who Needs to Register?
- Any person or business paid to interact with HMRC on behalf of someone else, about tax affairs. (gov.uk)
- Overseas advisers who assist UK clients also come under the rules. (gov.uk)
- Employees of such businesses do not need separate registration; registration applies to the legal entity. (gov.uk)
Exemptions & Edge Cases
- Providing free general tax or accounting education/training without advising on specific client cases. (gov.uk)
- Some roles already regulated or required by law, for example, insolvency practitioners. (gov.uk)
- Custom or tax software providers, or those acting only for payroll, import VAT, or customs representation may be exempt under certain conditions. (gov.uk)
Timeline
| Phase | Who must register from | Deadline window |
|---|---|---|
| 18 May – 18 August 2026 | New advisers, those without Agent Services Account (ASA), Self Assessment or Corporation Tax account | 18 August 2026 |
| 18 August – 18 November 2026 | Advisers with SA or CT account but no ASA | 18 November 2026 |
| 18 November 2026 – 18 February 2027 | Advisers providing only payroll services | 18 February 2027 |
| Until 31 March 2027 | Financial services organisations | 31 March 2027 |
Impacts on Digital Nomads & Small Firms
- If you engage a tax adviser (in the UK or overseas) to assist with your UK tax filings, confirm they are registered or in the process. Using unregistered advisers might have risks (advice quality, HMRC interactions).
- Small firms using freelance or overseas advisers need to review contracts and their adviser’s registration status.
What Advisers Must Do
- Apply for an Agent Services Account (ASA) if not already registered. (gov.uk)
- Provide identity and business details: UTR, company number, postcode, etc. (gov.uk)
- Monitor relevant individual employees: HMRC may require checks of those working in adviser businesses. (gov.uk)
Example Scenario
Sarah, a digital nomad permanently abroad but with UK property income, hires a tax adviser in her home country to file her UK Self Assessment. Under MMTAR, that overseas adviser must register if they contact HMRC on Sarah’s behalf and receive payment. If unregistered, Sarah could face risk of poor advice or complications if HMRC rejects claims.
Actions to Take Now
- If you are an adviser: review whether you meet the registration criteria and apply for ASA within your phase window.
- If you’re a taxpayer: check your adviser is validly registered; otherwise find a registered adviser with experience in your specific situation.
Conclusion
MMTAR will professionalise tax advice in the UK. Although many in established advisory firms will already be preparing, for small firms, remote workers, and international advisers, understanding these rules is essential to avoid non-compliance or advice that’s invalid.