42 CFR §457.610

The amount of a final allotment prior to FY 2009, as determined under § 457.608(h) and reduced to reflect certain Medicaid expenditures in accordance with § 457.616, remains available until expended for Federal payments based on expenditures claimed during a 3-year period of availability, beginning with the fiscal year of the final allotment and ending with the end of the second fiscal year following the fiscal year.