Legislation included in the Finance Act 2026 (Part 7 and Schedules 20 and 21) requires businesses interacting with HMRC in respect of another person’s tax affairs to register with HMRC. Mandatory registration will be phased in from 18 May 2026.

As explained in an earlier article, HMRC published initial guidance on the registration process in February 2026. HMRC has now published further high-level guidance explaining: 

• the consequences for the agent of continuing to interact with HMRC if they are unregistered or suspended as a tax adviser; and 
• the options open to the agent if they disagree with a decision made by HMRC. 

This guidance is summarised below. For in-depth analysis and discussion of the new requirements, listen to the latest episode of ICAEW’s The Tax Track podcast .   

Unregistered agents and HMRC’s powers to suspend registration 

From the date a tax adviser is required to register with HMRC, which could be as early as 18 May 2026, they should interact with HMRC only if they are registered as a tax adviser or have applied to register. HMRC may suspend an adviser’s registration where: 

• the adviser no longer meets the registration conditions; or
• HMRC considers that the agent’s behaviour falls below HMRC’s standard for agents.  

Once suspended, the agent will not be able to access their agent services account and should not interact with HMRC on behalf of clients in any other way.  

Suspension will work as follows: 

• Conditions no longer met. HMRC will give the adviser 30 days to correct the issues identified or to make representations (60 days for outstanding tax returns or unpaid tax). If the adviser does not correct the issues in that timeframe, HMRC may issue a notice of suspension. The suspension will start 30 days after the date of the notice of suspension and will be lifted once the issues have been resolved. 
• Behaviour is below the standard for agents. The agent may receive a fixed-term suspension. Agents will be given an initial 30-day period to make representations before HMRC decides to issue a suspension notice. The suspension will come into effect 30 days from the date on the notice and will last for up to 12 months. 

Reviews and appeals 

The decision to suspend an adviser’s registration is one of several decisions that HMRC may make in connection with mandatory tax adviser registration. Depending on the circumstances, the adviser may have the option to take up an offer to have the decision reviewed and/or appeal the decision.   

HMRC may offer the adviser the opportunity to have HMRC staff in a different team review the decision. This is referred to as ‘statutory review’. HMRC’s guidance explains how to accept the offer. The review usually takes up to 45 days. Once the review is completed, HMRC will confirm if the decision is upheld, altered or cancelled.  

The tax adviser can appeal to the tax tribunal instead of accepting HMRC’s offer of statutory review or after receiving the outcome of a statutory review.  

The adviser has 30 days from: 

• the date of the offer of a statutory review to accept the offer or to appeal to the tribunal. HMRC may allow the adviser to accept an offer after the time limit has expired where the adviser has a reasonable excuse for missing the deadline; and
• the date of the conclusion of a statutory review to appeal the outcome of the review to the tribunal.  

Temporary relief 

The adviser may be able to continue to interact with HMRC while their review or appeal is ongoing in some circumstances. This is referred to as ‘temporary relief’.  

If an application is made for temporary relief, it will be given automatically where the rejection or suspension is only because of outstanding tax returns or unpaid tax. In any other case, the adviser may apply to HMRC for temporary relief if they would be unable to continue as a going concern without it. HMRC will expect the adviser to provide evidence in support of their application. The adviser has the right of appeal against HMRC’s decision. 

HMRC says that it will update its guidance in due course to explain how an application for temporary relief may be made.  

Sanctions 

HMRC’s guidance sets out the sanctions that HMRC may impose on the adviser if they interact with HMRC while they are unregistered or their registration is suspended. Sanctions include financial penalties as well as temporary or permanent bans.

Further, advisers who are suspended or banned from interacting with HMRC must take reasonable steps to notify their clients, or face a penalty of £5,000 per client. This must be done within the period of 30 days beginning with: 

• in the case of a suspension lasting more than 30 days for failure to meet the registration conditions, the 31st day or the suspension; 
• in the case of a suspension due to the behaviour of the adviser, the day on which the suspension first has effect; and
• where a temporary or permanent ineligibility order has been issued, the day on which the order first has effect.   

HMRC may publish the adviser’s details where they are subject to a financial penalty or ban.  

Transition periods 

As explained in an earlier article, mandatory registration will be phased in from 18 May 2026, with the adviser’s start date depending on their characteristics. The adviser must register within three months of their start date (the transition period). HMRC’s guidance confirms that the adviser will not receive a sanction during the transition period if they have applied to HMRC and are waiting for HMRC’s decision.