When and how to enrol in Medicare

You can enrol in Medicare during your Initial Enrollment Period, which runs for seven months and includes the month you turn 65, plus three months before and three months after. If you miss this window, you can still enrol during the General Enrollment Period (January 1 to March 31 each year), but you may face a permanent late-enrollment penalty on your monthly premium.

To enrol, you have three main routes: online through Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. The online route is fastest — you can complete it in about 10 minutes if you have your Social Security number and birth date ready. The phone line has wait times but staff can walk you through the whole process and answer questions as you go.

You will need to provide your name, date of birth, Social Security number, and citizenship or permanent resident status. If you are already receiving Social Security benefits, Medicare will enrol you automatically in Part A (hospital insurance) and Part B (medical insurance) three months before your 65th birthday. You do not need to do anything unless you want to decline Part B or choose a different coverage option.

Key Takeaways

  • Your Initial Enrollment Period is seven months long — three months before you turn 65, the month you turn 65, and three months after — and missing it can cost you permanently in higher premiums.
  • You can enrol online at Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office, and the online route usually takes about 10 minutes.
  • If you are already getting Social Security payments, Medicare will enrol you automatically in Part A and Part B unless you actively decline Part B.
  • Part A (hospital insurance) is free for most people; Part B (medical insurance) has a monthly premium that varies by income and when you enrol.
  • If you miss your Initial Enrollment Period, you can still enrol during General Enrollment (January 1 to March 31), but you will pay a penalty for each month you delayed.

What happens if you enrol late

If you do not enrol in Part B during your Initial Enrollment Period and you do not have other may have access to coverage (such as employer health insurance), you will pay a 10 percent penalty on your Part B premium for each full year you were may be able to access but not enrolled. This penalty is permanent — it stays on your premium for as long as you have Medicare.

The same rule applies to Part D (prescription drug coverage). If you go 63 days or more without creditable drug coverage, you will pay a penalty when you finally enrol. The penalty amount depends on how long you went without coverage and changes each year.

There are exceptions: if you have employer coverage or retiree health insurance, you may not face a penalty when you enrol later. You will need to show proof of that coverage when you enrol. If you are still working and covered by your employer's plan, you can delay Part B without penalty, but you must enrol within eight months of leaving that job or losing the coverage.

Choosing between Original Medicare and Medicare Advantage

When you enrol, you will choose between Original Medicare (Part A and Part B) or a Medicare Advantage plan (Part C). Original Medicare is run by the federal government and covers hospital stays, doctor visits, and some preventive care. You can see any doctor or hospital that accepts Medicare, and there are no network restrictions.

Medicare Advantage plans are offered by private insurance companies and bundle Part A, Part B, and usually Part D (prescription drugs) into one plan. Most Advantage plans have lower monthly premiums than Original Medicare plus a separate Part D plan, but they typically require you to use doctors and hospitals within their network. You may also face higher out-of-pocket costs for specialist visits or hospital stays.

You do not have to choose right away. If you enrol in Original Medicare, you can switch to a Medicare Advantage plan during the Annual Enrollment Period (October 15 to December 7 each year). If you are in a Medicare Advantage plan, you can switch back to Original Medicare during the same window, though you should enrol in Part D at the same time if you want prescription drug coverage.

Adding prescription drug coverage and supplemental insurance

Part D (prescription drug coverage) is optional but recommended if you take regular medications. You can enrol in a Part D plan when you first enrol in Medicare, or during the Annual Enrollment Period. If you go without Part D for 63 days or more and then enrol later, you will pay a permanent penalty.

If you choose Original Medicare, you can also buy a Medigap (supplemental insurance) policy to cover costs that Medicare does not pay — such as copayments, coinsurance, and deductibles. Medigap plans are sold by private insurance companies and are standardized, meaning the same plan letter (Plan A, Plan B, Plan C, and so on) covers the same benefits no matter which company sells it. You have a six-month window starting the month you turn 65 and enrol in Part B to buy a Medigap policy without being denied or charged more for pre-existing conditions.

If you have a Medicare Advantage plan, you do not need Medigap because Advantage plans already include some out-of-pocket protections. Buying Medigap while you have an Advantage plan is usually a waste of money.

Documents and information you will need

Before you enrol, gather these items: your Social Security number, your birth date, your citizenship or permanent resident status (and a document proving it if you are not a U.S. citizen), and your current contact information (phone number and mailing address). If you are already receiving Social Security benefits, you will have most of this on file already.

If you are enrolling in a Medicare Advantage plan or Part D plan, you may also need a list of your current medications and doctors, so the plan can tell you whether they are covered. This is not required to enrol, but it helps you choose a plan that works for your health needs.

If you are delaying Part B because you have employer coverage, you will need to show proof of that coverage when you enrol later — usually a letter from your employer's benefits department or a copy of your health insurance card. Keep this document even after you leave the job, because you will need it to avoid a late-enrollment penalty.

What to expect after you enrol

Once you enrol, Medicare will send you a Medicare card in the mail within two weeks. Your coverage usually starts on the first day of the month after you enrol, though if you enrol between the 1st and 15th of a month, coverage can start that same month.

If you enrolled online or by phone, you will receive a confirmation number. Write it down or save it — you can use it to check the status of your enrolment on Medicare.gov or by calling 1-800-MEDICARE. If there are any problems with your enrolment, Medicare will contact you by mail or phone.

Once your coverage starts, you can use your Medicare card at any doctor's office, hospital, or pharmacy that accepts Medicare. If you chose a Medicare Advantage plan, your card will come from the insurance company, not from Medicare, and you will use it at in-network providers. If you chose Original Medicare and a Part D plan, you will receive a separate card for your prescription drug plan.

Enroling if you are not yet 65

You can enrol in Medicare before age 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). The rules are the same — you have a seven-month Initial Enrollment Period, and missing it can result in a permanent penalty.

If you are disabled and receiving SSDI, Medicare will enrol you automatically 24 months after your disability benefits begin. You do not need to do anything unless you want to decline Part B or choose different coverage. If you have ESRD or ALS, contact Social Security or Medicare directly to enrol, because the automatic process does not explore to these conditions.

Frequently Asked Questions

Can I enrol in Medicare before I turn 65?

Yes, if you have been receiving Social Security Disability Insurance for 24 months, or if you have end-stage renal disease or ALS. Otherwise, you must wait until the month you turn 65. If you are still working and have employer health insurance, you can delay Part B without penalty until you leave that job.

What if I miss my Initial Enrollment Period?

You can still enrol during General Enrollment (January 1 to March 31 each year), but you will pay a 10 percent penalty on your Part B premium for each full year you were may be able to access but not enrolled. This penalty is permanent. If you have a may have access to life event (such as losing employer coverage), you may have a Special Enrollment Period that lets you enrol without penalty.

Do I have to choose a plan right away, or can I change my mind later?

You can change your mind during the Annual Enrollment Period (October 15 to December 7 each year). If you enrol in Original Medicare, you can switch to a Medicare Advantage plan. If you are in an Advantage plan, you can switch back to Original Medicare. You can also change your Part D plan during this window.

What if I am still working when I turn 65?

If your employer has 20 or more employees and you are covered by their health plan, you can delay Part B without penalty. You must enrol within eight months of leaving the job or losing the coverage. If your employer has fewer than 20 employees, you should enrol in Part B when you turn 65 to avoid a penalty.

How much does Medicare cost?

Part A (hospital insurance) is free for most people who have paid Medicare taxes for at least 10 years. Part B (medical insurance) has a monthly premium that changes each year — in 2024 it ranges from $174.70 to $560.50 depending on your income. Part D and Medigap plans have their own premiums that vary by plan and location.