Compliance
What UK Tax Advisers Must Do: New Registration Rules (MMTAR) from May 2026
From 18 May 2026 the UK is introducing rolling registration requirements for anyone acting as a tax adviser to elevate standards and protect taxpayers.
By NomadicTax Research Team • 5-8 min read • May 17, 2026
## Overview of MMTAR: Modernising and Mandating Tax Adviser Registration
The UK is introducing a **mandatory registration system** for **all individuals paid for tax advice who interact with HMRC** on behalf of clients—this is known as **MMTAR**. Registration starts **18 May 2026**, with a phased rollout through to **March 2027**. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai)) Registration is free and replaces a variety of legacy paths. Its core aim: boost public trust, ensure consistency across the tax advice market, and help close the “tax advice” standards gap. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
## Key Dates & Categories
Below is the rollout schedule:
- **18 May → 18 August 2026**: New tax advisers, or those interacting with HMRC without an Agent Services Account (ASA), Self Assessment or Corporation Tax account.
- **18 August → 18 November 2026**: Advisers who have Self Assessment or Corporation Tax accounts but no ASA.
- **18 November 2026 → 18 February 2027**: Advisers who *only* provide payroll services.
- **31 December 2026 → 31 March 2027**: Final batch of advisers who need time to adjust and register. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
## Who Must Register & What’s Required
### Who?
- Anyone **paid** to give tax advice or act on behalf of clients with HMRC (Self Assessment, company tax, etc.).
- Includes overseas advisers interacting with UK tax matters.
- Some exemptions may apply (e.g. unpaid volunteers or certain public body roles). ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
### What documents/information required when registering:
- Government Gateway user ID & password (or ability to create one)
- Unique Taxpayer Reference (UTR)
- Company registration number or VAT registration number (if applicable)
- National Insurance number & date of birth (for sole traders/partnerships)
- Details of anti-money laundering supervisory body (if relevant)
Online registration becomes available **18 May 2026**, and must be done in stages as above. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
## Compliance Implications & Action Steps
- **Hold costumers’ compliance**: If you provide tax advice and are not registered when required, you may lose access to HMRC’s Agent Services Account or face restrictions.
- **Update internal records**: Ensure your practice has correct UTRs, ASA registrations, Identity documents ready.
- **Train staff**: Everyone giving advice needs to know whether they must register and adhere to HMRC’s conditions.
- **Use the interactive checker tool** on GOV.UK to determine your registration status. ([gov.uk](https://www.gov.uk/government/news/tax-advisers-check-if-you-need-to-register-under-new-rules?utm_source=openai))
## Example Scenario
Imagine **Acme Tax Consultancy**, a small firm with two staff who provide business tax and self-assessment tax advice:
- One partner deals with corporate accounts, already has ASA and interacts with HMRC—but no registration yet. They need to register between **18 August and 18 November 2026**.
- A new hire who will interact with HMRC and lacks an ASA or previous client accounts: they should be registered in the first phase (18 May-18 August).
If either fails, it might impact client trust, access to HMRC systems, or even run afoul of regulatory expectations.
## Takeaways
- **Check immediately** whether you and your staff are required to register under the new MMTAR rules.
- **Register in the correct phase**—don’t wait until deadline rush.
- **Ensure your identity and business credentials are accurate** and up-to-date.
- **Review exemptions**: some may not apply to you depending on the services you offer.
— With these steps, advisers can ensure compliance, maintain credibility, and position their practices for smoother interaction with HMRC under the new regime.