The 'additional agency check' indicates that a specific government digital service has additional authentication or authorisation requirements beyond what can be assigned in Corppass. Even after a service is assigned to a user in Corppass, certain services may require further verification steps. For example, ACRA restricts access to its BizFile service, allowing only authorised persons, such as local Directors, to make changes to company details.

To understand the specific requirements, you can visit the digital service’s website for details on the additional checks or contact the relevant government agency's helpdesk for assistance with their specific requirements.