Agents should use the normal channels for contacting HMRC in the first instance. These include HMRC’s helplines, the agent dedicated line, agent webchat and HMRC’s online tools. Further information, including contact details and links to HMRC’s guidance and tools, is provided by ICAEW at HMRC contact information | ICAEW.  

If the agent can’t resolve their query through the normal channels, they may be able to use one of HMRC’s resolution services. These include the personal tax query resolution service for agents (launched in March 2025) and the agent account manager service.  

When considering using one of HMRC’s resolution services, it is important that agents take the following action:  

• Understand their options. ICAEW’s webpage Report and resolve a tax problem | ICAEW provides a summary of, and links to the different routes available to agents. It also explains the differences between the two resolution services. To use one of the resolution services, the agent must first attempt to resolve their query through the normal channels. 
• Make sure they meet the eligibility criteria for using a resolution service. The conditions for using the resolution services are summarised at Report and resolve a tax problem | ICAEW, with links provided to further information. A key point to note is that the personal tax query resolution service for agents cannot be used for queries involving repayments. 
• Delay making a formal complaint to HMRC. The resolution services cannot be used if a formal complaint has been made to HMRC. Depending on the circumstances, agents may wish to consider using a resolution service before initiating a complaint. ICAEW’s webpage Making complaints to HMRC | Tax | ICAEW explains how to make a complaint. 
• Provide all relevant information and documents when initiating a query. This should reduce the need for follow-up contact from HMRC, helping HMRC to resolve the issue more quickly. 
• Look out for contact from HMRC. HMRC guidance is that agents should provide a phone number that accepts withheld numbers and to consider providing contact details for a second individual in case HMRC is unable to get in touch with the main contact.