(a) Total rebate. Subject to paragraph (b) of this section, the total rebate amount to be paid for a Part B rebatable drug, as identified under § 427.101, for an applicable calendar quarter is equal to the product of the per unit Part B rebate amount of such drug, as determined under § 427.302, and the billing units of the Part B rebatable drug furnished during the applicable calendar quarter, as identified as set forth in § 427.303. The rebate amount may be reduced as set forth in subpart E of this part or adjusted as set forth in subpart F of this part.

(b) Apportionment of the Part B rebate amount. CMS will identify billing and payment codes for which multiple manufacturers report ASP, as set forth in sections 1927(b)(3) and 1847A(f) of the Act, for NDCs assigned to the billing and payment code. CMS will calculate the rebate amount owed by each manufacturer by:

(1) Determining the total billing units sold for each NDC assigned to the billing and payment code, by multiplying the number of units reported by a manufacturer in ASP data submissions at the NDC-11 package level by the number of billing units per NDC-11 reporting unit.

(2) Summing the individual manufacturer's total billing units sold during the applicable calendar quarter (for all NDCs of the manufacturer assigned to the billing and payment code).

(3) Summing all manufacturers' total billing units sold during the applicable calendar quarter for all NDCs of the Part B rebatable drug assigned to the billing and payment code.

(4) Dividing the resulting amount from paragraph (b)(2) of this section by the resulting amount from paragraph (b)(3) of this section.

(5) Multiplying the resulting amount from paragraph (b)(4) of this section by the total rebate amount as determined under paragraph (a) of this section.

(c) Apportionment of the Part B rebate amount when reported units for NDCs within a billing and payment code are missing, negative, or equal to zero.

(1) When there are multiple NDCs in a grouped billing and payment code and the manufacturer-reported ASP units for all NDCs are either missing, negative, or equal to zero but there is a positive rebate amount calculated under § 427.302(a), CMS will:

(i) With respect to NDCs that were sold or marketed during the applicable calendar quarter and for which all NDCs assigned to the grouped billing and payment code lack manufacturer-reported ASP data for the applicable calendar quarter, equally apportion a positive rebate amount to NDCs with missing ASP units that were sold or marketed during the applicable calendar quarter by dividing the total rebate amount for the grouped billing and payment code by the total number of NDCs sold or marketed during the applicable calendar quarter within the billing and payment code; and

(ii) With respect to NDCs that were not sold or marketed during the applicable calendar quarter and lack manufacturer-reported ASP units for the applicable calendar quarter, NDCs with negative manufacturer-reported ASP units for the applicable calendar quarter, and NDCs with manufacturer-reported ASP units equal to zero for the applicable calendar quarter, apportion a $0 rebate amount to each respective NDC. If all NDCs assigned to the grouped billing and payment code are determined under this subparagraph, no rebate will be assessed for that billing and payment code.

(2) When there are multiple NDCs in a grouped billing and payment code and the manufacturer-reported ASP units for some but not all NDCs assigned to the grouped billing and payment code are either missing, negative, or equal to zero but there is a positive rebate amount calculated under § 427.302(a), CMS will:

(i) With respect to NDCs that were not sold or marketed during the applicable calendar quarter and lack manufacturer-reported ASP units for the applicable calendar quarter, NDCs with negative manufacturer-reported ASP units for the applicable calendar quarter, and NDCs with manufacturer-reported ASP units equal to zero for the applicable calendar quarter, apportion a $0 rebate amount to each respective NDC;

(ii) With respect to NDCs that were sold or marketed during the applicable calendar quarter and lack manufacturer-reported ASP units for the applicable calendar quarter, and NDCs that were sold or marketed during the applicable calendar quarter and for which respective NDCs have positive manufacturer-reported units by, apportion rebate amounts as follows:

(A) Solely for purposes of the calculation determined under this paragraph (c)(2)(ii) of this section, assign to NDCs that were sold or marketed during the applicable calendar quarter and lack manufacturer-reported ASP units for the applicable calendar quarter the number of ASP units that is equal to the lowest positive number of manufacturer reported ASP units for any NDC in the grouped billing and payment code;

(B) Determine the total billing units sold for each NDC assigned to the billing and payment code, by multiplying the number of units reported by a manufacturer in ASP data submissions at the NDC-11 package level by the number of billing units per NDC-11 reporting unit;

(C) With respect to all NDCs of each individual manufacturer assigned to the billing and payment code, sum the total billing units for such NDCs sold during the applicable calendar quarter;

(D) Sum the total billing units sold during the applicable calendar quarter for all NDCs of the Part B rebatable drug assigned to the billing and payment code, including those assigned a ASP unit value as set forth in paragraph (c)(2)(ii)(A) of this section;

(E) Divide the resulting amount from paragraph (c)(2)(ii)(C) of this section by the resulting amount from paragraph (c)(2)(ii)(D) of this section; and

(F) Multiply the resulting amount from paragraph (c)(2)(ii)(E) of this section by the total rebate amount as determined under paragraph (a) of this section.