Informal agency action is an action of an Administrative-agency other than adjudication, or rulemaking, such as investigation, publicity, or supervision. Informal agency action is an administrative agency activity which is not adjudication or rulemaking. The vast majority of agency actions are done informally. For example, every claim for payment for medical treatment rendered to a Medicare patient requires agency action. Medicare does this by setting out specific objective criteria for payment, many of which are set out in the Conditions of Participation, and they contract with private companies to check claims against the criteria.