26 C.F.R. § 54.9816-3

(a) The definitions in § 54.9801-2 apply to §§ 54.9816-4 through 54.9816-9, 54.9817-1, 54.9817-2, and 54.9822-1, unless otherwise specified. In addition, for purposes of §§ 54.9816-4 through 54.9816-9, 54.9817-1, 54.9817-2, and 54.9822-1, the following definition applies:

Bundled payment arrangement means an arrangement under which—

(1) A provider, facility, or provider of air ambulance services bills for multiple items or services furnished to a single patient under a single service code that represents multiple items or services (for example, a Diagnosis-Related Group (DRG) code); or

(2) A plan or issuer makes an initial payment or notice of denial of payment to a provider, facility, or provider of air ambulance services under a single service code that represents multiple items or services furnished to a single patient (for example, a DRG code).

(b) For further guidance, see 29 CFR 2590.716-3.