45 CFR § 150.303 - Basis for initiating an investigation of a potential violation.
(a) Information. Any information that indicates that any issuer may be failing to meet the PHS Act requirements or that any non-Federal governmental plan that is a group health plan as defined in section 2791(a)(1) of the PHS Act and 45 CFR § 144.103 may be failing to meet an applicable PHS Act requirement, may warrant an investigation. CMS may consider, but is not limited to, the following sources or types of information:
(3) Any other information that indicates potential noncompliance with PHS Act requirements.
(b) Who may file a complaint. Any entity or individual, or any entity or personal representative acting on that individual's behalf, may file a complaint with CMS if he or she believes that a right to which the aggrieved person is entitled under PHS Act requirements is being, or has been, denied or abridged as a result of any action or failure to act on the part of an issuer or other responsible entity as defined in § 150.305.
(c) Where a complaint should be directed. A complaint may be directed to any CMS regional office.