Applying Kisor v. Wilkie (2019) 139 S.Ct. 2400 and its analysis of Auer deference, this decision concludes that a decision of the HHS Departmental Review Board which interpreted an ambiguous HHS Medicare regulation was entitled to Auer deference. The Board’s interpretation was “authoritative” because the Board issues HHS’ final decision in contested cases, subject to federal court review. The interpretation implicated the agency’s core expertise because it involved administration of the Medicare program and the competing policies at stake in the particular issue to which the interpretation related. The interpretation was the agency’s fair and considered view because it did not create any unfair surprise having been stated in other agency guidance materials for a long time.