The Centers for Medicare & Medicaid Services Auditor Transparency Act of 2025, or CAT Act of 2025, seeks to improve transparency and due process for Medicare providers facing payment suspensions due to alleged fraud. Congress finds that current law grants broad authority to suspend payments without adequate transparency or due process, harming good-faith providers and potentially limiting beneficiary access to care. The bill aims to address these issues by amending Title XVIII of the Social Security Act. Specifically, the bill requires the Secretary of Health and Human Services to provide providers with detailed information about each credible allegation of fraud at least 30 days before a payment suspension begins, including the specific nature, date, and basis of the allegation. During a suspension, CMS must provide monthly updates on investigation findings, an anticipated timeline, and an opportunity for providers to ask questions. If these transparency requirements are not met, payments must be immediately resumed with accrued interest. The legislation also stipulates that investigations and payment suspensions may only exceed 180 days if the Secretary determines there is good cause for an extension. Furthermore, it expands the statutory definition of a "credible allegation of fraud" to include "mere error" and "billing error found during the course of an audit that is attributable to human error," alongside fraud hotline tips. This change, coupled with the new transparency rules, aims to ensure that even less severe issues are subject to proper scrutiny and provider recourse. Finally, the bill mandates the establishment of an independent appeals process within 180 days of enactment, allowing providers to challenge payment suspensions and receive timely resolutions. The Secretary is also required to submit an annual report to Congress detailing the number, basis, and duration of all payment suspensions and investigations.