The term “medicaid applicable income level” means, with respect to a child, the effective income level (expressed as a percent of the poverty line) that has been specified under the State plan under subchapter XIX of this chapter (including under a waiver authorized by the Secretary or under section
1396a
(r)(2) of this title), as of March 31, 1997, for the child to be eligible for medical assistance under section
1396a
(l)(2) or
1396d
(n)(2) of this title (as selected by a State) for the age of such child.