Authority to Operate (ATO)

An Authority to Operate (ATO) is the formal authorization from a senior official (the Authorizing Official) that permits an information system to operate in a production environment. It means the system's security risks have been evaluated and accepted — the system is approved for use.

An ATO is the end goal of the RMF process. It's granted after security controls have been assessed and any remaining risks have been formally accepted by the Authorizing Official. ATOs typically have an expiration period and must be renewed through continuous monitoring and periodic reassessment.

Without an ATO, a system cannot be connected to DoD or federal networks. Operating without authorization is a serious compliance violation.