Tax advisers check if you need to register under new rules

• From 18 May 2026, a new registration requirement for tax advisers will roll out.
• New mandatory tax adviser registration requirements will protect customers and raise standards in tax advice.
• Online registration will roll out in stages between 18 May 2026 and 31 March 2027. Registration is free, and step-by-step guidance is available on GOV.UK to help advisers understand what they need to do and when.

A new registration requirement for tax advisers, who are paid to interact with HM Revenue and Customs (HMRC) on behalf of clients, rolls out online from Monday 18 May 2026.

MMTAR was first announced at Budget 2025, following public consultation in 2024, as part of wider action to raise standards in the tax advice market and protect taxpayers. Consultation respondents were strongly in favour of tax adviser registration, which will help make advisers easier to identify, ensure consistent standards, and support those who play by the rules.

The government is investing £36 million to help HMRC modernise tax adviser registration and make it simpler for advisers to interact with the tax system as part of its Plan for Growth.

GOV.UK guidance about Modernising and Mandating Tax Adviser Registration (MMTAR) was published on 17 February 2026. Eligible tax advisers must meet HMRC’s registration conditions to apply for an agent services account (ASA).

Robert Jones, HMRC’s Director for Intermediaries, said

Tax advisers are encouraged to check the guidance now, to understand if and when they need to register, and prepare ahead of their registration window. We are taking action to raise standards in the tax advice market, support economic growth and help close the tax gap.  

These new registration requirements will create a fairer market for taxpayers, help them get more reliable advice, and support the majority of advisers who play by the rules.

It will be introduced gradually, with different groups invited to register at different stages

18 May to 18 August 2026

• New tax advisers, or advisers interacting with HMRC without an ASA, Self Assessment or Corporation Tax account.

18 August to 18 November 2026

• Advisers with a Self Assessment or Corporation Tax account, but without an ASA.

18 November 2026 to 18 February 2027

• Advisers who solely provide payroll services.

31 December 2026 to 31 March 2027

• Those who already have an ASA, and Financial services organisations. A full definition for this group will be published soon via secondary legislation.

Advisers will have three months from the start of their registration window to apply for an ASA. They can continue to interact with HMRC on behalf of their clients

• during these three months
• while HMRC considers their registration.

Registration is free, and step-by-step guidance is available on GOV.UK to help advisers understand what they need to do and when.

If a tax adviser already has an ASA, they do not need to register again. HMRC will contact them through their ASA if any additional information is needed to move them to the new digital system.

The following guidance is available on GOV.UK

Applying at the right time will help avoid delays and ensure advisers can continue supporting their clients without disruption.

Eligible advisers who do not register by the relevant deadline, or who fail to meet the required standards, will not be permitted to interact with HMRC on behalf of clients. Where advisers continue to act without registering, HMRC may apply sanctions, including financial penalties if they continue to interact with HMRC when told to stop.

Failing to register could also delay or disrupt services for clients and damage trust with individuals and businesses relying on professional tax support.

Further GOV.UK guidance is available

HMRC is working closely with the tax advice sector to support advisers through the phased roll out and help ensure those who need to register can do so smoothly.

Collectively, these changes mark a significant step in setting clearer expectations across the tax advice market and ensuring a smoother, more consistent and secure way for advisers to work with HMRC in future.

Further Information

If a person interacts with HMRC about someone else’s tax affairs and gets paid for it, HMRC considers them to be a ‘tax adviser’. This means they will need to register for an agent services account (ASA) – unless an exemption applies.

The requirement to register applies to all tax advisers and tax agents who interact with HMRC on behalf of clients and get paid for it.

The online registration service rolls out from Monday 18 May 2026. Details of ‘how to register’ online will be published on GOV.UK ahead of this date.

This requirement also applies to tax advisers based overseas who interact with HMRC on behalf of UK taxpayers.

To register, a tax adviser will need

• their Government Gateway user ID and password (if they do not already have one, they can create one from the sign in page)
• the Unique Taxpayer Reference (UTR) for their tax agent firm
• the postcode associated with their UTR
• their company registration number, if they have one
• their VAT registration number, if they have one
• their National Insurance number and Date of Birth to confirm their identity if they are a sole trader or business partnership
• their National Insurance number and Date of Birth to confirm their identity if they are a Limited Liability Partnership (in some cases)
• the name of their anti-money laundering supervisory body, membership number and renewal date

If agents or advisers do not provide tax advice as a business – for example, a voluntary sector organisation – they will not have to register.

There are exemptions for other types of activity, such as customs intermediation, set out in the guidance.

Guidance is available on GOV.UK, including information about who needs to register and who does not need to register.

HMRC has published a stakeholder pack with additional resources to support the MMTAR registration process.