Medicare and Medicaid are separate programs with different enrollment paths
Medicare is a federal health insurance program run by the Centers for Medicare & Medicaid Services (CMS). You become covered through Social Security, usually at age 65, or earlier if you have been receiving Social Security Disability Insurance (SSDI) for 24 months or have end-stage renal disease (ESRD). Medicaid is a joint federal and state program that covers people based on income and other factors that vary by state.
You can have both programs at the same time. When you do, Medicare is your primary insurance and Medicaid is secondary — it covers some costs Medicare does not. The way you enroll in each one is different, and the timing matters because missing a deadline can cost you.
This guide explains how each enrollment works, what documents you need, and what happens when you have both.
Key Takeaways
- Medicare enrollment happens through Social Security at age 65 or when you have received SSDI for 24 months; you do not have to do anything if you are already receiving Social Security benefits.
- Medicaid enrollment happens through your state's Medicaid office or health insurance marketplace, and income limits and covered services vary significantly by state.
- If you miss Medicare's initial enrollment window, you pay a permanent penalty on your premiums unless you had other health coverage or meet specific exceptions.
- When you have both programs, Medicare pays first and Medicaid covers remaining costs like copays and deductibles, which is why having both can lower your out-of-pocket expenses.
- You must report changes in income, household size, or living situation to Medicaid within 30 days, or you may lose coverage or pay back overpayments.
How Medicare enrollment works and when it starts
If you are receiving Social Security retirement benefits, Medicare Part A (hospital insurance) and Part B (medical insurance) start automatically the month you turn 65. You do not need to do anything. Social Security will mail you a Medicare card about three months before your 65th birthday.
If you are not yet receiving Social Security but will turn 65 soon, you can sign up for Medicare through Social Security's website, by phone at 1-800-772-1213, or in person at your local Social Security office. You should enroll during your initial enrollment period, which is the seven-month window that starts three months before the month you turn 65 and ends three months after. If you miss this window and do not have other health coverage, you will pay a permanent 10 percent increase to your Part B premium for as long as you have Medicare.
If you are under 65 and receiving SSDI, Medicare starts automatically after you have been on SSDI for 24 months. If you have ESRD (permanent kidney failure), you can enroll in Medicare regardless of age, but you must do so within three months of starting dialysis or receiving a kidney transplant.
How Medicaid enrollment works and what your state requires
Medicaid is run by each state, so the income limits, covered services, and enrollment process differ. Some states use a continuous enrollment system where you can apply any time; others have specific enrollment periods. You can find your state's Medicaid office through the Centers for Medicare & Medicaid Services website or by calling 1-800-MEDICARE.
To enroll in Medicaid, you will need to provide proof of income (recent pay stubs, tax returns, or a letter from Social Security showing your benefit amount), proof of citizenship or immigration status, and proof of residency in your state. Some states also ask for proof of age and identity. You can apply online through your state's Medicaid portal, by mail, in person at your local Medicaid office, or through a community health center or hospital social worker.
Processing time varies by state but typically takes 30 to 45 days. Some states offer expedited processing for people over 65 or with disabilities, which can take as little as 7 to 10 days. If your state approves you, coverage usually starts on the first day of the month in which you applied, though some states backdate coverage to the first day of the month you became income-may be able to access.
Income limits and how they affect both programs
Medicare has no income limit — anyone who meets the age or disability requirement can enroll. Medicaid income limits vary by state and household size. In 2024, states that expanded Medicaid under the Affordable Care Act generally cover people with income up to 138 percent of the federal poverty level, which is roughly $1,900 per month for a single person. States that did not expand Medicaid have lower limits, sometimes as low as 50 percent of the federal poverty level.
If you receive both Medicare and Medicaid, you are often called a dual-may be able to access beneficiary. Your Medicare benefits do not change based on Medicaid, but Medicaid will cover some of your Medicare costs. Specifically, Medicaid can pay your Medicare Part B premiums, your Part A and Part B deductibles and copays, and your Part D (prescription drug) copays. This is why dual coverage can significantly reduce your out-of-pocket costs.
If your income rises above your state's Medicaid limit, you will lose Medicaid coverage but keep Medicare. If your income drops below the limit, you can reapply to Medicaid at any time.
Documents you need to enroll in each program
| Program | Required Documents | Where to Submit |
|---|---|---|
| Medicare | Social Security number, proof of age (birth certificate), proof of citizenship or permanent residency | Social Security Administration office, online at ssa.gov, or by phone at 1-800-772-1213 |
| Medicaid | Proof of income (pay stubs, tax returns, Social Security statement), proof of citizenship or immigration status, proof of state residency, proof of age and identity | Your state's Medicaid office, online portal, or local health department |
Keep copies of everything you submit. If your state or Social Security asks for more information, they will send you a notice with a deadline — usually 10 to 30 days. If you miss the deadline, your application may be denied and you will have to reapply.
What happens after you are enrolled in both programs
Once you have Medicare and Medicaid, you will receive two separate insurance cards — one from Medicare and one from your state's Medicaid program. When you see a doctor or go to a hospital, show both cards. The provider will bill Medicare first, and Medicare will pay its share. Then the provider will bill Medicaid for any remaining balance, and Medicaid will pay what it covers under your state's rules.
You must report any changes to Medicaid within 30 days. Changes include a new job or job loss, a change in income, a move to a different address, a change in household size (marriage, divorce, birth, death), or a change in citizenship status. You do not need to report changes to Medicare unless they affect your Social Security benefits.
If you move to a different state, your Medicare coverage continues, but your Medicaid coverage ends on the last day of the month you move. You must apply for Medicaid in your new state. Some states have a grace period that allows you to keep coverage for a short time while you apply, but do not count on it — apply as soon as you move.
Special enrollment periods and exceptions to the enrollment deadline
If you miss Medicare's initial enrollment period, you can still enroll without a penalty if you had other health coverage that was considered creditable coverage — meaning it was at least as good as Medicare Part B. Creditable coverage includes employer health insurance, TRICARE (military insurance), or coverage through a spouse's job. You have eight months after your coverage ends to enroll in Medicare without penalty.
For Medicaid, most states allow you to apply at any time, but some have limited enrollment periods if you are not in a special circumstance. Special circumstances include losing other health coverage, having a baby, getting married or divorced, or experiencing a change in income. If you are over 65 or have a disability, most states let you apply year-round.
Frequently Asked Questions
Do I have to enroll in Medicare Part D (prescription drug coverage) if I have Medicaid?
Not necessarily. If your state's Medicaid program covers prescription drugs, you may not need Part D. However, if you do not enroll in Part D when you first become may be able to access and later lose Medicaid coverage, you will pay a permanent penalty on Part D premiums. It is often safer to enroll in Part D even if you do not use it right away.
What if I am under 65 and have both SSDI and Medicaid?
You will become may be able to access for Medicare automatically after 24 months on SSDI. At that point, you will have both programs. Your state's Medicaid office should be notified by Social Security, but confirm that your Medicaid coverage continues after Medicare starts. Some states require you to reapply or update your information.
Can I lose Medicaid if my Medicare benefits increase?
It depends on your state. Some states count only non-Medicare income toward the Medicaid limit, so an increase in Medicare benefits does not affect your Medicaid. Other states count all income, including Medicare. Check with your state's Medicaid office about how they count your income.
What if I think I was denied Medicaid unfairly?
You have the right to appeal. Your state will send you a notice explaining why you were denied and how to request a hearing. You usually have 30 to 60 days to file an appeal. You can represent yourself or bring someone to help you. Contact your state's Medicaid office for the appeal process.
Do I need to do anything when I turn 65 if I already have Medicaid?
Medicare will start automatically if you are receiving Social Security. Your Medicaid will continue, and you will become dual-may be able to access. Confirm with your state's Medicaid office that they know about your Medicare enrollment so they can coordinate benefits correctly.