On Aug. 18, 2026, UK HMRC updated its current Mandatory tax adviser registration — communications resources webpage, to reflect that mandatory registration has been introduced for tax advisers who are paid to interact with UK HMRC on behalf of clients.
On the same day, UK HMRC opened the second phase of mandatory tax adviser registration, with the remaining eligible advisers required to register by Nov. 18, 2026.
All advisers with Self Assessment or Corporation Tax accounts, but without an agent services account (ASA), now need to register to ensure relevant future compliance.
Advisers who solely provide professional payroll services do not need to register before Nov. 18, 2026, and Financial Services bodies must all register before Dec. 31, 2026.
These mandatory changes are designed to raise standards in the tax advice market, protect taxpayers, as well as supporting all of those providers who play by the rules.
Registering on time will help advisers continue supporting clients without disruption and maintain trust that individuals and businesses place in professional tax services.
All of the advisers who missed the first registration window, or who are new entrants to the tax advice market, should now all register as soon as possible, within this window.
UK HMRC may limit an adviser’s ability to act on behalf of clients if they fail to register.
In addition, any advisers who continue to operate without completing the registration requirement could also face some enforcement action, including financial penalties.
Registration is free and online, and step-by-step guidance and an interactive checker tool are available on GOV.UK to help all advisers to understand if they need to register.
On Feb. 17, UK HMRC issued guidance for tax advisers re registration.
UK HMRC issued guidance to clarify if and when firms must register as a tax adviser with UK HMRC; and guidance for tax advisers to help them check if they meet the conditions to register with UK HMRC and interact on behalf of their clients.
Follows UK HMRC Nov. 2025 issued policy paper on mandatory registration, #277764.
Entities That Must Register
Defines a tax adviser who interacts with UK HMRC about someone else’s tax affairs and get paid for it; the tax advisor needs to register for an agent services account.
The guidance clarifies who does not need to register, such as an employer or in-house tax team, running payroll for its own staff, providing tax advice services for free.
A tax adviser needs to register for an agent services account from May 18, 2026.
Registration Conditions
Business will need to meet certain conditions when registering for an agent services account; some people working for the business also need to meet the conditions.
These people are known as relevant individuals.
If a business has 5 officers or less, UK HMRC will treat them all as relevant individuals.
If a business has 6 officers or more, the business need to notify UK HMRC about all the relevant individuals, who include all officers involved in tax adviser activities.
The guidance specifies the registration conditions for business including that the business must not have any relevant outstanding tax returns or unpaid tax.
Plus the registration conditions for relevant individuals.
Overseas tax advisers will need to be able to send authenticated evidence to UK HMRC when registering for an agent services account.
Effectiveness
The registration starts from May 18, 2026.
Apr. 2026 Unregistered and Suspended Advisors
On Apr. 30, 2026, UK HMRC published another guidance webpage titled What happens if you interact with HMRC when you are unregistered or suspended as a tax adviser.
From May 18, 2026, those who intend to interact with UK HMRC about someone else’s tax affairs and get paid for it may need to register as a tax adviser with UK HMRC.
Adviser and relevant individuals, will also need to meet HMRC’s registration conditions.
UK HMRC may issue a penalty to an adviser if it interacts with UK HMRC whilst the firm is unregistered, or the tax adviser registration is suspended, with interacting definition including contacting UK HMRC directly and sending returns, claims or other documents.
For those registered to interact with UK HMRC on behalf of clients, it may suspend the tax adviser registration if a business or a relevant individual no longer meets HMRC’s registration conditions, or its behavior falls below the UK HMRC’s standard for agents.
UK HMRC will contact firms if the business or any relevant individuals no longer meet registration conditions, and given 30 days from date of contact to correct any issues.
If the issues are not corrected within specified time, UK HMRC will issue a notice of suspension, which will then start 30 days after the date of the notice of suspension.
The penalties that can be issued include financial, from £5,000 to £10,000, and/or temporary or permanent ineligibility orders, banning the firm's operation as adviser.
UK HMRC may also publish details about the firm, as well as the penalties applied.
If a tax adviser registration is suspended for over 30 days or they receive a temporary or permanent ban, they must take reasonable steps to notify clients within 30 days.
Jul. 2026 Registration Reminder
On Jul. 20, 2026, UK HMRC issued a press release entitled Tax advisers: one month left to register under new rules, urging eligible tax advisers to register under the new mandatory requirements before Aug. 18, 2026, to avoid disruption to their clients.
UK HMRC is encouraging anyone who has not yet registered with them, to check if they need to and submit their application as soon as possible, to meet the new requirement.
The first phase of Modernising and Mandating Tax Adviser Registration (MMTAR) closes on 18 August 2026 for new tax advisers, or advisers interacting with UK HMRC without an agent services account (ASA), or via a Self Assessment or Corporation Tax account.
Advisers who already have an ASA do not need to register again at this stage and UK HMRC will contact them directly if additional information is required for new system.
UK HMRC’s Director of Intermediaries, Robert Jones, commented these requirements will help create a fairer, more transparent tax advice market, support those advisers who meet high standards, and give taxpayers confidence in the advice they receive.
Aug. 2026 Second Registration Window
On Aug. 18, 2026, UK HMRC updated its current Mandatory tax adviser registration — communications resources webpage, to reflect that mandatory registration has been introduced for tax advisers who are paid to interact with UK HMRC on behalf of clients.
On the same day, UK HMRC opened the second phase of mandatory tax adviser registration, with the remaining eligible advisers required to register by Nov. 18, 2026.
All advisers with Self Assessment or Corporation Tax accounts, but without an agent services account (ASA), now need to register to ensure relevant future compliance.
Advisers who solely provide professional payroll services do not need to register before Nov. 18, 2026, and Financial Services bodies must all register before Dec. 31, 2026.
These mandatory changes are designed to raise standards in the tax advice market, protect taxpayers, as well as supporting all of those providers who play by the rules.
Registering on time will help advisers continue supporting clients without disruption and maintain trust that individuals and businesses place in professional tax services.
All of the advisers who missed the first registration window, or who are new entrants to the tax advice market, should now all register as soon as possible, within this window.
UK HMRC may limit an adviser’s ability to act on behalf of clients if they fail to register.
In addition, any advisers who continue to operate without completing the registration requirement could also face some enforcement action, including financial penalties.
Registration is free and online, and step-by-step guidance and an interactive checker tool are available on GOV.UK to help all advisers to understand if they need to register.
