How Medicaid Is Administered: Federal and State Roles

Medicaid operates as a joint federal-state program, meaning no single level of government controls it entirely. Federal law sets the floor — minimum eligibility rules, required benefits, and spending conditions — while each state builds its own program on top of that foundation. The result is 50 distinct state Medicaid programs, plus programs in the District of Columbia and U.S. territories, all operating under a shared statutory framework. Understanding this division of authority is essential for anyone analyzing coverage decisions, benefit disputes, or state-level policy variation.

Definition and scope

Medicaid is authorized under Title XIX of the Social Security Act (42 U.S.C. § 1396 et seq.), enacted in 1965. The program finances medical services for qualifying low-income individuals, including children, pregnant women, adults in expansion states, people with disabilities, and elderly individuals who meet income and asset thresholds. The Medicaid.gov program overview describes it as the single largest source of health coverage in the United States, covering more than 80 million individuals as of federal enrollment data published by the Centers for Medicare & Medicaid Services (CMS).

The scope of the program spans acute care, long-term services and supports (LTSS), behavioral health, and preventive services. Federal law mandates a set of required benefits — inpatient and outpatient hospital services, physician services, laboratory and X-ray services, and nursing facility services for adults, among others. States may also elect to offer optional benefits such as prescription drugs, physical therapy, and dental services for adults. For a broader view of the program's dimensions, see the Key Dimensions and Scopes of Medicaid page.

How it works

The administrative relationship between the federal government and states is governed by a State Plan — a formal agreement that each state submits to CMS describing how it will operate its Medicaid program. Any significant departure from the approved plan requires a State Plan Amendment (SPA) or a waiver under Section 1115 or 1915 of the Social Security Act.

Financing runs through a matching formula called the Federal Medical Assistance Percentage (FMAP). The FMAP is calculated annually using each state's per capita income relative to the national average (42 U.S.C. § 1396d(b)). States with lower per capita income receive a higher federal match. The standard FMAP ranges from 50 percent (the statutory floor) to approximately 83 percent for the lowest-income states. Enhanced rates apply in specific contexts — for example, the Affordable Care Act set the federal match for newly eligible expansion adults at 90 percent beginning in 2020 (42 U.S.C. § 1396d(y)).

Day-to-day program administration falls to each state's designated Medicaid agency, which determines eligibility, enrolls beneficiaries, contracts with managed care organizations or operates fee-for-service systems, and processes claims. CMS retains oversight authority, conducts audits, approves or rejects State Plan Amendments, and issues guidance through informational bulletins and State Medicaid Director letters.

The administrative layers break down as follows:

1. Federal level (CMS): Sets minimum standards via regulation and sub-regulatory guidance; approves State Plans and waivers; calculates and disburses federal matching funds; conducts program integrity reviews.
2. State Medicaid agency: Administers eligibility determinations; manages provider enrollment; oversees managed care contracts; submits required financial and utilization reports to CMS.
3. Managed care organizations (MCOs) or fee-for-service networks: Deliver or coordinate covered services directly to beneficiaries under contracts with the state.

Common scenarios

Three patterns illustrate how the federal-state relationship operates in practice:

Eligibility disputes. A state may restrict eligibility more narrowly than federal minimums only in ways permitted by statute. States cannot, for example, impose a work requirement without an approved Section 1115 waiver. When a waiver is granted, CMS monitors compliance against the specific terms approved in the waiver document.

Benefit design variation. Two states may offer identical mandatory benefits but diverge substantially on optional benefits. Texas, for instance, does not cover all optional adult dental services that California covers under Denti-Cal. Both programs are legally compliant because optional benefit selection is a state prerogative under Title XIX.

Managed care expansion. A state wishing to move its entire Medicaid population into managed care must submit a Section 1915(b) waiver or operate under a Section 1115 demonstration. CMS evaluates whether the proposal maintains beneficiary access and protections equivalent to fee-for-service standards before granting approval.

Decision boundaries

The clearest functional boundary is between what states must do and what they may do:

A second boundary separates administrative decisions that require only a State Plan Amendment from those requiring a waiver. Routine eligibility expansions and benefit additions generally proceed through the SPA process; structural changes to delivery systems, eligibility conditions tied to behavior, or restrictions on required benefits trigger the waiver pathway, which carries additional federal scrutiny and time-limited approval periods.

The Medicaid frequently asked questions resource addresses specific eligibility scenarios. For assistance navigating state-specific program rules, the How to Get Help for Medicaid page identifies official state agency contacts and enrollment resources. The Medicaid Authority home page provides a structured entry point to the full range of program topics covered across this reference resource.