In this menu, scroll down to the “Manage Tax Agents” section. Below this title, click on the hyperlink labeled “All Other Tax Agent Services.”

On the next screen with an older layout, locate the “About You” section and find the “Agent Details” section. Click the link labeled “Authorise an Agent.”

At this stage, enter the agent code provided by your agent in the designated field and click “Next.”

The final step is to confirm that the correct agent details appear based on the agent code you provided. If everything looks correct, check the box and click “Next.”

Once completed, this will authorize the agent to communicate with HMRC regarding your Self Assessment matters.