reference month
(4) Computation of statutory market share percentage (A) In general The Secretary shall determine for each year a statutory national market share percentage that is equal to the proportion of MA eligible individuals nationally who were not enrolled in an MA plan during the reference month. (B) Reference month defined For purposes of this part, the term “reference month” means, with respect to a year, the most recent month during the previous year for which the Secretary determines that data are available to compute the percentage specified in subparagraph (A) and other relevant percentages under this part.