Medicare is our country's health insurance program for people age 65 or older. Certain people younger than age 65 can qualify for Medicare too, including those with disabilities and those who have permanent kidney failure.
The program helps with the cost of health care, but it does not cover all medical expenses or the cost of most long-term care. You have choices for how you get Medicare coverage. If you choose to have Original Medicare (Part A and Part B) coverage, you can buy a Medicare Supplement Insurance (Medigap) policy from a private insurance company.
The Parts of Medicare
Social Security enrolls you in Original Medicare (Part A and Part B).
- Medicare Part A (hospital insurance) helps pay for inpatient care in a hospital or limited time at a skilled nursing facility (following a hospital stay). Part A also pays for some home health care and hospice care.
- Medicare Part B (medical insurance) helps pay for services from doctors and other health care providers, outpatient care, home health care, durable medical equipment, and some preventive services.
Other parts of Medicare are run by private insurance companies that follow rules set by Medicare.
- Supplemental (Medigap) policies help pay Medicare out-of-pocket copayments, coinsurance, and deductible expenses.
- Medicare Advantage Plan (also known as Part C) includes all benefits and services covered under Part A and Part B — prescription drugs and additional benefits such as vision, hearing, and dental — bundled together in 1 plan.
- Medicare Part D (Medicare prescription drug coverage) helps cover the cost of prescription drugs.
Most people age 65 or older are eligible for free Medicare Part A (hospital insurance) if they have worked and paid Medicare taxes long enough. You can sign up for Medicare Part B (medical insurance) by paying a monthly premium. Some beneficiaries with higher incomes will pay a higher monthly Part B premium. To learn more, read Medicare Premiums: Rules For Higher-Income Beneficiaries.
Should I Sign Up For Part B (Medical Insurance)?
With our online application, you can sign up for Medicare Part A and Part B. Because you must pay a premium for Part B coverage, you can opt out of that coverage.
If you’re eligible at age 65, your Initial Enrollment Period (IEP) begins 3 months before your 65th birthday, includes the month you turn age 65, and ends 3 months after that birthday.
If you accept the automatic enrollment in Medicare Part B or if you sign up during the first 3 months of your IEP, your coverage will start the month you’re first eligible. If you sign up during the month you turn 65 or during the last 3 months of your IEP, your coverage starts the 1st day of the month after you sign up.
The following chart shows when your Medicare Part B becomes effective in 2023:
|If you enroll in this month of your IEP||Your Part B Medicare coverage starts|
|1 to 3 months before you reach age 65||The month you turn age 65.|
|The month you reach age 65, or 1 to 3 months after you reach age 65||The 1st day of the month after you sign up.|
If you choose not to sign up for Medicare Part B but then decide to do so later, your coverage could be delayed. You may have to pay a higher monthly premium for as long as you have Part B. Your monthly premium will go up 10% for each 12-month period you were eligible for Part B but didn’t sign up for it. This does not apply if you qualify for a "Special Enrollment Period" (SEP).
If you don’t sign up for Medicare Part B during your IEP, you have another chance each year to sign up during the “General Enrollment Period” (GEP) from January 1 through March 31. Your coverage starts the 1st day of the month after you sign up. Read our publication Medicare for more information.
Special Enrollment Period (SEP)
You may have medical insurance coverage under a group health plan based on your or your spouse's current employment. In this case you may not need to apply for Medicare Part B at age 65. You may qualify for an "SEP” that will let you sign up for Part B during:
- Any month you remain covered under the group health plan and you or your spouse's employment continues.
- The 8-month period that begins with the month after your group health plan coverage or the employment it is based on ends, whichever comes first.
How to Apply Online for Just Medicare
Are you within 3 months of turning age 65 or older and not ready to start your monthly Social Security benefits yet? You can use our online application to sign up just for Medicare and wait to apply for your retirement or spouses benefits later. It takes less than 10 minutes, and there are no forms to sign and usually no documentation is required.
To find out what documents and information you need to apply, go to the Checklist for Online Medicare, Retirement, and Spouses Applications.
To help protect your identity, your Medicare card has a Medicare number that’s unique to you. If you did not receive your red, white, and blue Medicare card, there may be something that needs to be corrected, like your mailing address. You can update your mailing address by signing in to or creating your personal my Social Security account. Learn more about your Medicare card.
Already Enrolled in Medicare
If you have Medicare, you can get information and services online. Find out how to manage your benefits.
If you are enrolled in Medicare Part A and you want to sign up for Part B, please complete form CMS-40B, Application for Enrollment in Medicare – Part B (medical insurance). If you are applying for Medicare Part B due to a loss of employment or group health coverage, you will also need to complete form CMS-L564, Request for Employment Information.
You can use 1 of the following options to submit your enrollment request under the Special Enrollment Period:
- Go to “Apply Online for Medicare Part B During a Special Enrollment Period” and complete CMS-40B and CMS-L564. Then upload your evidence of Group Health Plan or Large Group Health Plan.
- Fax or mail your CMS-40B, CMS-L564, and secondary evidence to your local Social Security office (see list of secondary evidence below).
- State “I want Part B coverage to begin (MM/YY)” in the remarks section of the CMS-40B form or online application.
- If possible, your employer should complete Section B.
- If your employer is unable to complete Section B, please complete that portion as best as you can on their behalf and submit 1 of the following forms of secondary evidence:
- Income tax form that shows health insurance premiums paid.
- W-2s reflecting pre-tax medical contributions.
- Pay stubs that reflect health insurance premium deductions.
- Health insurance cards with a policy effective date.
- Explanations of benefits paid by the GHP or LGHP.
- Statements or receipts that reflect payment of health insurance premiums.
You’ll have Original Medicare (Part A and Part B) unless you make another choice. You can decide to add a drug plan (Part D) or buy a Medigap policy to help pay for costs that Original Medicare doesn’t cover. You can choose to join a Medicare Advantage Plan (Part C) and get all your Medicare coverage bundled together in 1 plan. This coverage includes drugs and extra benefits like vision, hearing, dental, and more.
Some people with limited resources and income may also be able to get Extra Help to pay for Part D drug costs.
What Happens After I Apply?
The Centers for Medicare & Medicaid Services (CMS) manages Medicare. After you are enrolled, they will send you a Welcome to Medicare packet in the mail with your Medicare card. You will also receive the Medicare & You handbook, with important information about your Medicare coverage choices.
Medicare Enrollment in Puerto Rico
- Who do I contact - Social Security or Medicare?
- Apply Online for Medicare — Even if You Are Not Ready to Retire
- Help Fight Medicare Fraud
- Get Extra Help with Medicare prescription drug plan costs
- More Medicare information
- Understanding Medicare Part C & D Enrollment Periods
- Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare
- Understanding Medicare Advantage Plans
- Mandatory Medicare Coverage
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