; and (4) provide guidance to such State agencies with respect to State oversight of efforts under a medicaid managed care plan under section 1903(m) or 1932 to assess such liability. . (e) Development of model uniform fields for States To report third party information Not later than January 1, 2019, the Secretary of Health and Human Services shall, in consultation with the States, develop and make available to the States a model uniform reporting field that States may use for purposes of reporting to the Secretary through the Transformed Medicaid Statistical Information System (T–MSIS) (or a successor system), or within CMS Form 64 (or any successor form), information identifying responsible third parties (as defined in subsection (nn) of section 1902 of the Social Security Act ( 42 U.S.C. 1396a ), as added by subsection (a)(2)(A)) and other relevant information for ascertaining the legal responsibility of such third parties to pay for care and services available under the State plan (or under a waiver of the plan) under title XIX of the Social Security Act ( 42 U.S.C. 1396 et seq.). (f) Effective date (1) In general Except as provided in paragraph (2), this section and the amendments made by this section (other than as specified in the preceding provisions of this section) shall take effect on October 1, 2019, and shall apply to medical assistance or child health assistance provided on or after such date. (2) Exception if State legislation required In the case of a State plan for medical assistance under title XIX of the Social Security Act ( 42 U.S.C. 1396 et seq.), or a State child health plan for child health assistance under title XXI of such Act ( 42 U.S.C. 1397aa et seq.), that the Secretary of Health and Human Services determines requires State legislation (other than legislation appropriating funds) in order for the plan to meet the additional requirement imposed by the amendments made under this section, such plan shall not be regarded as failing to comply with the requirements of such title solely on