42 CFR § 440.305 - Scope.
(a) General. This subpart sets out requirements for States that elect to provide medical assistance to certain Medicaid eligible individuals within one or more groups of individuals specified by the State, through enrollment of the individuals in coverage, identified as “benchmark” or “benchmark-equivalent.” Groups must be identified by characteristics of individuals rather than the amount or level of FMAP.
(b) Limitations. A State may only apply the option in paragraph (a) of this section for an individual whose eligibility is based on an eligibility category under section 1905(a) of the Act that could have been covered under the State's plan on or before February 8, 2006, except that individuals who are eligible under section 1902(a)(10)(A)(i)(VIII) of the Act must enroll in an Alternative Benefit Plan to receive medical assistance.
(c) A State may not require but may offer enrollment in benchmark or benchmark-equivalent coverage to the Medicaid eligible individuals listed in § 440.315. States allowing individuals to voluntarily enroll must be in compliance with the rules specified at § 440.320.