ASC proportion
(3) (A) The aggregate amount of the payments to be made under this part for outpatient hospital facility services or critical access hospital services furnished before January 1, 1999 , in connection with surgical procedures specified under paragraph (1)(A) shall be equal to the lesser of— (i) the amount determined with respect to such services under subsection (a)(2)(B); or (ii) the blend amount (described in subparagraph (B)). (B) (i) The blend amount for a cost reporting period is the sum of— (I) the cost proportion (as defined in clause (ii)(I)) of the amount described in subparagraph (A)(i), and (II) the ASC proportion (as defined in clause (ii)(II)) of the standard overhead amount payable with respect to the same surgical procedure as if it were provided in an ambulatory surgical center in the same area, as determined under paragraph (2)(A), less the amount a provider may charge as described in clause (ii) of section 1395cc(a)(2)(A) of this title . (ii) Subject to paragraph (4), in this paragraph: (I) The term “cost proportion” means 75 percent for cost reporting periods beginning in fiscal year 1988, 50 percent for portions of cost reporting periods beginning on or after October 1, 1988 , and ending on or before December 31, 1990 , and 42 percent for portions of cost reporting periods beginning on or after January 1, 1991 . (II) The term “ASC proportion” means 25 percent for cost reporting periods beginning in fiscal year 1988, 50 percent for portions of cost reporting periods beginning on or after October 1, 1988 , and ending on or before December 31, 1990 , and 58 percent for portions of cost reporting periods beginning on or after January 1, 1991 .