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You’ll be automatically enrolled in Medicare at age 65 if you’re already receiving Social Security. If you aren’t receiving those benefits, you can enroll in one of three ways:
The online application typically takes less than 10 minutes. The Social Security Administration has suspended face-to-face service in local offices due to the COVID-19 pandemic, so no in-person visits are possible at this time. It's planning to reopen some offices later in 2022, but most Medicare enrollment is quick and easy online.
Medicare is available to all U.S. adults age 65 or older. It's also available to younger people who get Social Security disability benefits, or SSDI. Usually, they’re enrolled in Medicare automatically after 24 months of disability benefit eligibility.
» MORE: Who qualifies for Medicare?
People who have Lou Gehrig’s disease, also known as ALS, automatically receive Medicare coverage the same month that they get their first disability check. People with kidney failure (end-stage renal disease) can apply for Medicare, with coverage typically starting on the first day of the fourth month of dialysis treatments. Retroactive start dates are common, going back as many as 12 months. If certain conditions are met, the waiting period may be waived.
When to sign up for Medicare
If you’re not enrolled automatically, you should sign up in the three months before your 65th birthday. That way, coverage will start on the first day of your birthday month (unless you were born on the first day of the month, in which case coverage begins on the first day of the prior month).
You technically have seven months around your 65th birthday to enroll: the three months before your birthday month, your birthday month and the three months after. This is called your initial enrollment period. If your birthday is the first of the month, your initial enrollment period includes the four months before your birthday month and two months after.
Your coverage could be delayed if you wait until your birthday month or the three months afterward to apply for Medicare. And if you miss your initial window, you may need to sign up during Medicare's general enrollment period. However, you may be subject to a permanent penalty unless you have continuous coverage from a large employer group health insurance plan.
General enrollment period
If you don't apply during your initial enrollment period for Parts A and B, and you're not eligible for a special enrollment period, you'll have to wait for Medicare's general enrollment period to sign up. This is different from the annual open enrollment period.
The general enrollment period runs from Jan. 1 to March 31 every year. Coverage doesn't start until July 1 of the year you enroll, and late penalties may apply. You will also pay for any health costs you incur during the time you were uninsured before your coverage begins.
People who are enrolled automatically are generally enrolled at the same time in both Medicare Part A — which covers hospitals — and Medicare Part B, which covers doctor visits. Part A normally doesn’t have premiums, but Part B does.
People who enroll themselves often choose both Part A and Part B together, although many can delay signing up for Part B because they have other coverage. Once employer group health insurance is ending, it’s important to proactively enroll in Part B if you previously delayed this part of Medicare. There could be penalties for delaying, so make sure you understand the rules.
Prescription drug coverage is available through a private insurance company's Medicare Part D plan. There may be penalties if you go without Part D or other acceptable drug coverage (known as "creditable" coverage from an employer or union health insurance plan) for too long, so make sure you understand these rules as well.
You also can opt for additional coverage from private insurance companies. Many people buy Medicare Supplement Insurance, or Medigap, to cover copays, deductibles and other expenses Medicare doesn’t cover. You have a six-month period after starting Part B to select a supplemental policy without any medical underwriting. The insurer you choose can’t turn you down or charge you more for preexisting conditions or other health-related issues. After your one-time, initial enrollment window, a Medigap policy might cost more or you may not be able to get one at all, depending on your health situation, unless a "guaranteed issue" applies.
Another private insurance option to consider is Medicare Advantage, also known as Part C. These plans include all the benefits offered by Medicare Part A and Part B, as well as additional cost-sharing provisions. You need to be enrolled in Medicare Parts A and B to buy a Medicare Advantage plan. There are various enrollment periods around your specific situation. However, if you're enrolling in Medicare for the first time during your initial enrollment period, you typically also buy your Medicare Advantage plan then as well.
» MORE: Best Medicare Advantage plans
Medicare late enrollment penalties
If you’re not automatically enrolled in Medicare and you don’t apply on time, you may face late enrollment fees:
Medicare Part A: If you must buy Part A and you don’t purchase it during your initial enrollment period, you may owe 10% more than the monthly premium for twice the time period you didn’t sign up.
Medicare Part B: If you don’t sign up for Part B during your initial enrollment period, your monthly premium increases 10% for each 12-month period that you went without Part B coverage. This is a permanent penalty as long as you have Part B.
Medicare Part D: If you go without Medicare drug coverage or other creditable prescription drug coverage for 63 or more days once your initial enrollment period ends, you'll be assessed a permanent penalty for as long as you have Medicare drug coverage. The penalty is calculated as 1% of the “national base beneficiary premium” multiplied by the number of full months you weren’t covered. (There is no cap. If you don’t think you need Part D for 72 months, that’s a 72% penalty.) Your exact penalty amount is recalculated each year.
What happens after you sign up for Medicare
After you sign up for Medicare, you’ll be mailed a Medicare welcome kit explaining how Parts A and B work and how to shop for additional coverage. You’ll also get your red, white and blue Medicare card. (Don’t throw it away — it’s not junk mail.)
The date your coverage starts will depend on when you sign up for Medicare:
When you sign up
When your Medicare coverage starts
Before the month of your 65th birthday.*
The month you turn 65.
The month you turn 65.
The next month.
One month after you turn 65.
Two months after you sign up.
Two or three months after you turn 65.
Three months after you sign up.
During the general enrollment period, which runs Jan. 1 to March 31 each year.
During a special enrollment period.
The next month.
*If your birthday is on the first of the month, your coverage will start on the first day of the month before your birthday month. For example, if you turn 65 on August 1, your coverage will start on July 1.
Coverage always starts on the first day of the month. If you’re unsure of when you can sign up for Medicare, check your specific situation with Medicare directly.
What Medicare covers
Medicare covers a lot of things — but not everything. Find out where Medicare stands in the following areas: