Medicaid rebates were first required by the federal Omnibus Budget Reconciliation Act of 1990 that required drug manufacturers to sign a rebate agreement with the Secretary of the U.S. Department of Health and Human Services in order to have their drugs covered by state Medicaid programs. The rebate agreement requires manufacturers to pay the state the greater of a basic rebate of 15.1% or a rebate equal to the difference between the manufacturer price and the lowest price available from the manufacturer to any other private purchaser within the U.S.; this is known as the “best price.” States also receive an additional rebate if the cost of the drug exceeds the consumer price index in any given quarter.