The Centers for Medicare & Medicaid Services (CMS) -- a federal agency within the Department of Health and Human Services (HHS) -- and states jointly administer and fund the Medicaid program. States have flexibility within broad federal requirements to design and implement their Medicaid programs. States must submit a state Medicaid plan to CMS for review and approval. A states approved Medicaid plan outlines the services provided and the groups of individuals covered. While states must cover certain mandatory populations and benefits, they have the option of covering other categories of individuals and benefits.