Where the Centers for Medicare and Medicaid Services Is Based and How It Operates

The Centers for Medicare and Medicaid Services is a federal agency based in Baltimore, Maryland

The Centers for Medicare and Medicaid Services (CMS) is the federal agency that runs Medicare, Medicaid, and the Children's Health Insurance Program (CHIP). Its main office is located in Baltimore, Maryland, where the agency was established in 1965 as part of the Social Security Administration. CMS became its own agency in 1977 and has been headquartered in Baltimore ever since.

CMS is part of the U.S. Department of Health and Human Services (HHS). The agency employs thousands of people across its Baltimore headquarters and regional offices spread throughout the country. If you have a Medicare question or need to report a problem, you will likely interact with CMS staff either by phone, mail, or through its website — but the decisions and policies that shape your Medicare coverage originate from this central office in Maryland.

Key Takeaways

CMS is headquartered in Baltimore, Maryland, and has been since it became an independent agency in 1977.
The agency operates 10 regional offices across the United States to handle Medicare and Medicaid matters in different parts of the country.
CMS was created in 1965 as part of the Social Security Administration when Medicare and Medicaid were first established.
You can contact CMS through Medicare.gov, by calling 1-800-MEDICARE, or by visiting a local Social Security office for help with Medicare questions.

How CMS is organized and what it does

CMS operates through several divisions that handle different parts of the Medicare and Medicaid programs. The Center for Medicare manages the Medicare program — Parts A, B, D, and Medicare Advantage plans. The Center for Medicaid and CHIP Services handles state Medicaid programs and CHIP. A third division oversees quality and safety standards for hospitals, nursing homes, and other healthcare facilities that receive Medicare or Medicaid payment.

The agency also runs the Health Insurance Marketplace, where people under 65 can shop for coverage under the Affordable Care Act. CMS sets the rules for what Medicare covers, how much it pays doctors and hospitals, and what beneficiaries have to pay out of pocket. When you receive a Medicare bill or have a coverage question, the answer comes from a policy or decision made by CMS.

CMS regional offices and local contact points

Although CMS is based in Baltimore, the agency operates 10 regional offices across the United States. These regional offices handle Medicare and Medicaid matters for specific states and territories. For example, the Boston regional office covers New England, the Philadelphia office covers the Mid-Atlantic states, and the Chicago office covers the Midwest. Each region has staff who work with state agencies, hospitals, and beneficiaries on local Medicare and Medicaid issues.

You do not need to contact a regional office directly for most Medicare questions. Instead, you can call 1-800-MEDICARE (1-800-633-4227), which routes your call to the right place based on your state and question. You can also visit Medicare.gov to find contact information for your state's Medicare office or your local Social Security office, which handles Medicare enrollment and some benefit questions.

When CMS was created and why

Congress created Medicare and Medicaid in 1965 as part of President Lyndon B. Johnson's Great Society legislation. At that time, both programs were placed under the Social Security Administration. As the programs grew and became more complex, the government separated Medicare and Medicaid into their own agency in 1977, which became the Health Care Financing Administration (HCFA). In 2001, HCFA was renamed the Centers for Medicare and Medicaid Services to better reflect its broader role in healthcare.

The decision to create CMS as a separate agency reflected the growing importance of Medicare and Medicaid to the healthcare system. By the 1970s, these programs covered millions of people and required dedicated staff and infrastructure. Moving them out of the Social Security Administration allowed the agency to focus entirely on managing healthcare coverage and payment — a job that has only grown more complex over the decades.

How to reach CMS if you have a problem

If you have a Medicare issue that you cannot resolve through your insurance company or doctor's office, you can contact CMS directly. The main phone line is 1-800-MEDICARE. This number connects you to customer service representatives who can answer questions about coverage, billing, and enrollment. The line is open 24 hours a day, seven days a week, and you can speak to someone in your preferred language.

You can also file a complaint with CMS if you believe you have been treated unfairly or if a provider has violated Medicare rules. Complaints can be submitted through Medicare.gov or by calling 1-800-MEDICARE. CMS also has a website where you can look up information about hospitals, nursing homes, and other healthcare facilities, including their safety records and patient satisfaction scores.

Understanding CMS's role in your Medicare coverage

CMS does not provide Medicare coverage directly — instead, it contracts with private insurance companies to administer the program. For Original Medicare (Parts A and B), CMS works with regional Medicare Administrative Contractors (MACs) who process claims and handle customer service in your area. For Medicare Advantage and Part D plans, CMS oversees private insurers that offer these plans but does not run them itself.

This means that when you have a question about your Medicare bill or coverage, you may need to contact your insurance company first. However, if your insurance company is not following CMS rules or if you disagree with a coverage decision, you can appeal to CMS or file a complaint. Understanding that CMS sets the rules but does not always handle the day-to-day work can help you know who to contact when you need help.

Frequently Asked Questions

Can I visit the CMS office in Baltimore if I have a Medicare problem?

CMS does not have a walk-in office for the public. You will need to contact CMS by phone at 1-800-MEDICARE or through Medicare.gov. If you prefer to speak with someone in person, you can visit your local Social Security office, which can help with Medicare enrollment and some benefit questions.

Is CMS the same as Medicare?

No. CMS is the federal agency that runs Medicare, Medicaid, and CHIP. Medicare is the health insurance program itself. CMS makes the rules and policies, while insurance companies and healthcare providers carry out the day-to-day work of processing claims and providing care.

What if I disagree with a CMS decision about my coverage?

You have the right to appeal any Medicare coverage decision. You can start by asking your insurance company or healthcare provider to reconsider. If you disagree with their decision, you can file a formal appeal with CMS. Instructions for appeals are included in any coverage denial letter you receive.

Does CMS handle Medicaid in my state?

CMS oversees Medicaid nationwide, but each state runs its own Medicaid program with CMS oversight. If you have a Medicaid question, contact your state's Medicaid office first. CMS can help if you believe your state is not following federal Medicaid rules.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.