The Department of Health and Human Services (HHS) must utilize notice-and-comment rulemaking to promulgate rules, requirements, or statements of policy that "establish or change" a "substantive legal standard" governing payment for services under the Medicare Act, 42 U.S.C. 1395hh(a)(2). See 42 U.S.C. 1395hh(b)(l). The question presented is: Whether Section 1395hh(a)(2) requires HHS to conduct notice-and-comment rulemaking before providing instructions to a Medicare Administrative Contractor that makes initial determinations of payments due under Medicare, when those instructions rest on a non-(cid:173) legally-binding administrative interpretation of a relevant statutory provision. LIMITED TO THE FOLLOWING QUESTION: WHETHER 42 U.S.C. §1395hh(a)(2) or §1395hh(a)(4) REQUIRED THE DEPARTMENT OF HEALTH AND HUMAN SERVICES TO CONDUCT NOTICE-AND-COMMENT RULEMAKING BEFORE PROVIDING THE CHALLENGED INSTRUCTIONS TO A MEDICARE ADMINISTRATOR CONTRACTOR MAKING INITIAL DETERMINATIONS OF PAYMENTS DUE UNDER MEDICARE.