To register for online filing as an agent with HMRC you'll need an Agent Reference Number. Apply to your local tax office or apply online via the HMRC Online Services if you're overseas.
Once you've received your Agent Reference Number, follow these steps:
- Go to the New user page on the HMRC website.
- Click on Agent.
- Tick the services you want to use.
- If you want to complete and file company tax returns, tick Self Assessment (SA) for Agents and Corporation Tax (CT) for Agents (if applicable).
- Work through the rest of the pages.