The Centers for Medicare and Medicaid Services runs both Medicare and Medicaid

The Centers for Medicare and Medicaid Services (CMS) is the federal agency inside the U.S. Department of Health and Human Services that administers Medicare, Medicaid, and the Children's Health Insurance Program (CHIP). If you receive Medicaid, CMS sets the rules that your state's Medicaid program must follow, though your state runs the day-to-day work of enrolling people and paying providers.

CMS does not run Medicaid directly in your state. Instead, it funds Medicaid, sets minimum standards for what coverage must include, and oversees whether states are following federal law. Your state's Medicaid agency — often called the Department of Social Services or Department of Health — is the office you actually contact to enroll or report changes.

Understanding this split matters because it explains why Medicaid rules vary by state, why you may hear different information from different offices, and why some questions need to go to CMS while others go to your state.

Key Takeaways

  • CMS is a federal agency that sets rules for Medicaid, but your state runs its own Medicaid program and decides how to carry out those rules within federal limits.
  • CMS also runs Medicare (for people 65 and older) and CHIP (for children in families that earn too much for Medicaid but not enough for private insurance).
  • If you need to enroll in Medicaid or report a change, you contact your state Medicaid office, not CMS directly.
  • CMS publishes official guidance on Medicaid rules, coverage requirements, and state policies on its website, which can help you understand what your state must cover.

How CMS and your state Medicaid program divide the work

CMS writes the federal rules that all state Medicaid programs must follow. These rules cover who can enroll, what services must be covered, how much providers get paid, and how states must process applications. But CMS does not process your application or decide whether you are enrolled.

Your state Medicaid agency does that work. It takes your application, verifies your income and household size, determines whether you meet your state's rules, and sends you a notice of approval or denial. Your state also decides how to run its program within the federal framework — for example, which optional services to cover beyond what CMS requires, how much to pay doctors and hospitals, and whether to expand Medicaid to adults earning up to 138% of the federal poverty level.

This is why two people in different states with identical income and family size may have different Medicaid coverage. CMS sets the floor; your state builds on top of it.

What CMS oversees beyond Medicaid

CMS runs three major programs: Medicare (health insurance for people 65 and older, some younger people with disabilities, and people with end-stage renal disease), Medicaid (joint federal-state coverage for low-income people), and CHIP (coverage for children in families earning between the Medicaid limit and about 200% of the federal poverty level).

CMS also regulates nursing homes, hospitals, and other healthcare providers to make sure they meet federal standards. If you have a complaint about a nursing home or hospital, CMS investigates through its state survey agencies. CMS also runs the Health Insurance Marketplace, where people can shop for private insurance plans and see if they may have access to for subsidies.

How to find official CMS information about Medicaid

CMS publishes official guidance on its website at cms.gov. The Medicaid section includes state-by-state information, coverage rules, and links to each state's Medicaid program. If you want to know what your state must cover or what federal rules say about a specific situation, CMS's website is the authoritative source.

However, CMS's website is written for healthcare professionals and state administrators, not for people applying for coverage. The language is technical, and pages can be hard to navigate. For plain-language information about how to apply or what Medicaid covers in your state, your state Medicaid office's website is usually clearer.

You can find your state Medicaid office through the CMS website or by searching "[your state] Medicaid" online. Most states also have a 1-800 number for Medicaid questions.

Why CMS matters when your state denies your application

If your state Medicaid office denies your application and you believe they made a mistake, you have the right to request a fair hearing. That hearing is conducted by your state, but the hearing officer must apply CMS's federal rules correctly. If your state is not following federal law, CMS can investigate and require your state to fix the problem.

You do not contact CMS directly to appeal a denial. Instead, you ask your state for a fair hearing, and you can mention in your appeal that your state's decision violates federal Medicaid rules. If you believe your state is systematically breaking federal law, you can file a complaint with CMS's Office of Inspector General, but this is a slow process and does not help your individual case quickly.

The difference between CMS guidance and your state's actual rules

CMS publishes guidance documents that explain how federal Medicaid law should work. But your state can interpret that guidance differently, and sometimes states do things that go beyond what CMS requires. This creates confusion because a CMS document might say one thing, and your state's policy might say another.

For example, CMS requires states to cover certain services, but a state might cover additional services that CMS does not require. Or CMS might say a state can do something, but your state chooses not to. When you are trying to figure out what Medicaid covers for you, your state's rules are what actually apply to your case — not the CMS guidance.

If you think your state is not following CMS's rules, you can ask your state Medicaid office to explain the difference. If they cannot give you a clear answer, you can contact your state's Medicaid ombudsman or a legal aid office for help.

Frequently Asked Questions

Do I contact CMS or my state if I have a question about my Medicaid?

Contact your state Medicaid office first. CMS does not handle individual cases. Your state processes applications, approvals, and changes to your coverage. If your state cannot help or you believe they are breaking federal law, then you can escalate to CMS, but that is a longer process.

Can CMS override my state's Medicaid decision?

CMS can investigate if your state is not following federal law and can require your state to fix the problem. But CMS does not overturn individual decisions. You must first request a fair hearing from your state. If your state's hearing officer makes a decision that violates federal law, you can then appeal to CMS, though this is rare and takes months.

Does CMS run Medicaid in my state?

No. CMS sets the rules and funds Medicaid, but your state runs it. Your state decides how to carry out those rules, which optional services to cover, and how much to pay providers — all within federal limits. This is why Medicaid looks different in each state.

What is the difference between CMS and my state's Medicaid office?

CMS is the federal agency that writes the rules and oversees all state programs. Your state's Medicaid office is the local agency that enrolls you, processes your application, and manages your coverage. You deal with your state; CMS watches to make sure your state follows the law.

Where can I find what my state's Medicaid program covers?

Start with your state Medicaid office's website — search "[your state] Medicaid" or call the number on your Medicaid card. CMS's website also has links to each state's program and publishes what services CMS requires states to cover, though your state may cover more.