[Last updated October 2, 2025]
Medicare, the federal health insurance program for adults 65 and over and some younger adults with certain conditions or disabilities, provides essential coverage to help individuals maintain their health and access necessary medical services. Understanding who qualifies, when to sign up, and how to apply for Medicare can seem overwhelming. This comprehensive guide breaks down everything you need to know about Medicare eligibility and the application process.
What is Medicare?
Medicare is a federal health insurance program that covers a comprehensive range of medical services for older adults over 65 and younger individuals with disabilities, end-stage renal disease, or ALS.
Here’s how Medicare coverage works:
| Medicare part | Coverage type | What it includes |
| Part A | Hospital insurance | Inpatient hospitalization, skilled nursing facilities, home health care, and hospice care |
| Part B | Medical insurance | Doctor visits, preventive services, durable medical equipment, and outpatient care |
| Part C | Medicare Advantage | Alternative to original Medicare (includes Parts A and B and often Part D) |
| Part D | Prescription drug coverage | Prescription medications and related services |
While Medicare provides robust coverage for most health-related concerns, beneficiaries may still have out-of-pocket costs. Responsibility for deductibles, copayments, and coinsurance will depend on their chosen plan.
Who is eligible for Medicare?
Who qualifies for Medicare is determined by age and specific health conditions. People who are U.S. citizens or permanent residents are eligible for Medicare at age 65. Younger individuals with a qualifying disability, end-stage renal disease (permanent kidney failure requiring dialysis or a transplant), or ALS (also called Lou Gehrig’s disease) are also eligible.
When to apply for Medicare
Knowing when to sign up for Medicare is crucial to avoid coverage gaps and late enrollment penalties. Understanding the enrollment periods helps ensure a seamless transition to coverage. Here are the three enrollment periods:
Applying for Medicare when turning 65
Your initial enrollment period is a seven-month window surrounding your 65th birthday. It includes:
- The three months before your birth month.
- Your birth month.
- The three months following your birth month.
If you’ve been receiving Social Security benefits before turning 65, you’ll be automatically enrolled in Medicare Parts A and B when you turn 65. Otherwise, you must actively sign up online or by calling 1-800-772-1213 during the initial enrollment period.
Applying for Medicare after turning 65 under special circumstances
Certain situations open up special enrollment periods. Enrollment during these periods protects you against late enrollment penalties even when signing up for Medicare after turning 65. Some events that qualify you for special enrollment periods include:
- Having had health insurance through your employer.
- Losing Medicaid coverage.
- Being impacted by a natural disaster or emergency.
- Moving outside your plan’s service area.
- Receiving misinformation from the health plan or employer.
- Being released from incarceration.
Applying for Medicare after turning 65 without qualifying for a special enrollment period
If you miss your initial enrollment period and don’t qualify for a special enrollment period, you can apply for Medicare during the next general enrollment period, which runs from January 1 through March 31 each year. Coverage starts the month after enrollment.
This delay may result in lifelong penalties when you do enroll.
Late enrollment penalties
Penalties can be incurred for late enrollment in Parts A, B, and D.
- Part A: For most people, Part A premiums are free, so there is no penalty for late enrollment. However, if you have to pay for Part A, your premium could go up by 10% for twice the number of years you went without Part A coverage.
- Part B: Your penalty for late enrollment in Part B will be an extra 10% for each year you could have signed up but didn’t (e.g., 20% if you didn’t sign up for two years). The penalty will last for as long as you have Part B coverage.
- Part D: You won’t pay a Part D penalty if you have qualifying drug coverage elsewhere or qualify for Medicare’s Extra Help program. If you don’t join when you first get Medicare or go 63 days or more without qualifying coverage, you will pay an extra 1% of the national average premium for each month you didn’t sign up. This penalty lasts as long as you have Part D coverage.
What decisions do I need to make when signing up for Medicare?
The primary decision involves choosing between original Medicare and a Medicare Advantage plan. Let’s look at their basic characteristics:
Original Medicare (Parts A and B)
Original Medicare is a fee-for-service program with nationwide provider access that covers about 80% of Medicare-approved costs. Many people purchase a Medigap plan (supplemental insurance) to help cover some of the 20% balance and a private prescription drug plan (Part D) to cover prescribed medications.
Advantages:
- Access to any doctor or hospital nationwide that accepts Medicare.
- Predictable coverage structure.
- Freedom to see specialists without referrals.
Limitations:
- Open-ended out-of-pocket exposure unless you buy a Medigap plan.
- Additional premiums for Part D and Medigap policies on top of your Part B premium.
Medicare Advantage (Part C)
Medicare Advantage plans are a private insurance alternative to original Medicare that covers Parts A, B, and often D. Unless the plan you choose doesn’t include Part D, you won’t need to purchase any other policies.
Advantages:
- Usually low or $0 monthly premiums (but you must pay the Part B premium).
- Additional benefits often included (e.g., dental, vision, hearing).
- Integrated prescription drug coverage for many plans.
Limitations:
- Restricted provider network.
- Limited geographic service area.
- Frequent referral requirement for specialists.
How to apply for Medicare
How to apply for Medicare depends on whether you choose original Medicare or Medicare Advantage.
If you’re applying for original Medicare, you will need the following information:
- Social Security number.
- Place of birth.
- Current health insurance details.
- Valid email address (if applying for Part B only).
- Medicare number (if applying for Part B only).
Your application options for original Medicare include:
- Online application: Apply through the Social Security Administration website after setting up your My Social Security account. This is the most convenient and fastest application method.
- Phone application: To complete your Medicare Parts A and B application by phone, speak with a representative by calling 1-800-772-1213 (the primary number) or 1-800-325-0778 (for TTY users).
- In-person application: Visit your local Social Security Administration office. Find locations using the SSA office locator on their website.
If you’re applying for Medicare Advantage, you must first enroll in Medicare Parts A and B. Be sure to compare all available plans in your area before making your selection, considering networks, costs, and additional benefits.
Your application options include:
- Calling 1-800-MEDICARE (1-800-633-4227) for plan information.
- Researching plans online at Medicare.gov.
- Contacting Medicare Advantage providers directly.
- Working with licensed insurance brokers.
Making changes to your Medicare coverage
After you enroll in your preferred Medicare coverage, if you change your mind, you can make changes during the open enrollment period, which runs from October 15 through December 7 each year. During that period, you can:
- Switch between original Medicare and Medicare Advantage.
- Change between Medicare Advantage plans.
- Add or drop prescription drug coverage.
Note: Depending on your timing, switching from Medicare Advantage back to original Medicare may limit the availability of Medigap policies, lead to denied coverage, or result in higher premiums.
Understand your options when applying for Medicare
Taking time to research and understand your Medicare options ensures you’ll choose the best plan for your unique health care needs and financial situation. The options can make your decision feel complex, so don’t hesitate to seek available resources for help. With proper preparation, you can approach applying for Medicare with confidence and peace of mind.
