In tender documentation, the ACS said the new identity management system would be installed at its Canberra site, and "possibly" Sydney.
The ACS wants a comprehensive system based on off-the-shelf software, including the ability to archive all events like identity creation and password resets for audit records. The system must also generate cryptographic keys for secure access, according to the tender.
The system had been called for due to acknowledged flaws in the ACS' current infrastructure.
"The Customs environment consists of non-standard, independently managed information and IT solutions with identity and access management processes that pose challenges to the security, privacy and efficiency of the organisation," the tender document said.
The system is part of the ACS' overall identity management strategy, which aims to address risk and audit requirements over the next three to five years.
The system must integrate with Microsoft's Active Directory, according to the tender, which the ACS plans to adopt as part of the strategy.
Active Directory would be the "vital authoritative source" of resource identity information, according to the tender.
Customs uses Microsoft Windows platforms on both the server and desktop.
A disaster recovery plan for the system is also to be provided by the successful tenderer.
Customs said it expected to execute a contract for the system by June 13.