Medicare starts at 65 for most people, but enrollment windows open before that birthday

You become may be able to access for Medicare on the first day of the month you turn 65. If your birthday falls on the first of any month, that is your Medicare start date. If your birthday is any other day, Medicare begins on the first day of the following month. You do not have to wait until you turn 65 to sign up — in fact, you should enroll during your initial enrollment period, which starts three months before the month you turn 65 and ends three months after.

The enrollment window matters because signing up late can cost you. If you miss your initial enrollment period and do not have coverage through an employer or union, you will pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare. That penalty is roughly 10 percent per year of delay, added to your regular premium.

Some people become may be able to access before 65. If you have been receiving Social Security disability benefits for 24 months, or if you have end-stage renal disease or ALS, you can enroll in Medicare regardless of age.

Key Takeaways

  • Medicare may be able to access begins the first day of the month you turn 65, or the first day of the month after your birthday if you were not born on the first.
  • Your initial enrollment period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
  • Enrolling late in Part B or Part D triggers a permanent penalty on your premiums unless you had employer or union coverage that delayed your need to sign up.
  • You can enroll in Medicare before 65 if you have been on Social Security disability for 24 months, or if you have end-stage renal disease or ALS.
  • You enroll through Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office.

What happens during your initial enrollment period

Your initial enrollment period is seven months long. It starts three months before the month you turn 65 and ends three months after. During this window, you can enroll in Part A (hospital insurance) and Part B (medical insurance) without penalty, and you can choose a Part D drug plan or a Medicare Advantage plan.

Most people do not need to do anything to get Part A. If you are already receiving Social Security benefits, Medicare Part A is automatic — it starts the month you turn 65 with no action required. If you are not yet on Social Security, you will need to sign up for both Social Security and Medicare at the same time, or sign up for Medicare separately through Medicare.gov or by calling 1-800-MEDICARE.

Part B is different. You must actively choose to enroll. Part B covers doctor visits, outpatient care, and some preventive services. If you have health insurance through your employer or union and you are still working, you may be able to delay Part B enrollment without penalty — but you have to tell Medicare that you have this coverage. The coverage must be based on your current work, not your spouse's work.

Employer coverage and delayed enrollment

If you are still working at 65 and your employer offers health insurance, you can turn down Medicare Part B and stay on your employer plan instead. You will not face a late-enrollment penalty if you sign up for Part B later, as long as your employer coverage is based on your own current employment. Once you leave that job or lose the coverage, you have eight months to enroll in Part B without penalty.

The same rule applies if you have coverage through a union or through your spouse's employer. The key is that the coverage must be active and based on current work. Retiree health plans do not count — if you are already retired, you cannot delay Part B enrollment.

If you are unsure whether your coverage qualifies, contact your employer's benefits office or call Medicare at 1-800-MEDICARE. Getting this wrong is expensive, so it is worth confirming before you turn down Part B.

Enrolling in Part D and Medicare Advantage during your window

Part D is prescription drug coverage. You can enroll during your initial enrollment period, or you can wait and enroll during the annual open enrollment period from October 15 to December 7 each year. However, if you do not have drug coverage and you miss your initial enrollment period, you will pay a penalty for every month you were without it — roughly 1 percent of the national average Part D premium per month of delay. That penalty is permanent and stays with you even after you enroll.

Medicare Advantage (Part C) is an alternative to Original Medicare. Instead of Part A and Part B, you choose a single plan run by a private insurance company. Medicare Advantage plans usually include drug coverage and may offer dental, vision, or hearing benefits. You can enroll in Medicare Advantage during your initial enrollment period, or during the annual open enrollment period.

If you enroll in Original Medicare (Part A and Part B) first, you can still switch to Medicare Advantage later, but you have limited windows to do so. The easiest time is during the annual open enrollment period or during the Medicare Advantage open enrollment period from January 1 to March 31 each year.

What to do if you miss your initial enrollment period

If you pass your initial enrollment period without enrolling, you can still sign up, but you will face penalties. For Part B, the penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. For Part D, the penalty is roughly 1 percent of the national average premium per month of delay. Both penalties are permanent — they do not go away once you enroll.

The exception is if you had coverage through an employer or union based on current work. In that case, you have eight months after you lose that coverage to enroll without penalty. You will need to provide proof of your employer coverage — usually a letter from your employer's benefits office stating the dates you were covered.

If you are already on Social Security and you miss your initial enrollment period, you may be able to enroll during a general enrollment period from January 1 to March 31 each year. Coverage would start July 1 of that year. This route does not avoid the late-enrollment penalty, but it does get you covered.

Turning 65 while still working

Turning 65 does not mean you have to retire. If you are still working and your employer offers health insurance, you can stay on that plan and delay Medicare enrollment. You do not have to take Social Security at 65 either — you can keep working and delay Social Security to get a higher monthly benefit later.

However, you do need to tell Medicare that you have employer coverage if you want to avoid the Part B penalty. You can do this by calling 1-800-MEDICARE or by visiting Medicare.gov. Without this notification, Medicare may assume you turned down Part B deliberately and assess a penalty when you finally enroll.

If your employer plan ends while you are still working — because you change jobs, the company stops offering coverage, or you are laid off — you have eight months to enroll in Medicare Part B without penalty. The clock starts the month your coverage ends, not the month you enroll in a new plan.

Special situations: disability, ESRD, and ALS

You can enroll in Medicare before 65 if you have been receiving Social Security disability benefits for 24 consecutive months. Your Medicare coverage begins the 25th month of your disability benefit. You do not have to do anything — Medicare is automatic once you hit that 24-month mark.

If you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or a transplant — you can enroll in Medicare regardless of age. Your enrollment period is three months before the month dialysis or a transplant is scheduled, the month of the procedure, and three months after. If you are already on dialysis when you learn about Medicare, you can enroll during a special enrollment period.

If you have ALS (amyotrophic lateral sclerosis), you become may be able to access for Medicare when ready upon approval for Social Security disability benefits. You do not have to wait 24 months like other disability beneficiaries. Medicare coverage begins the same month your disability benefits start.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Only if you have been on Social Security disability for 24 months, or if you have end-stage renal disease or ALS. Otherwise, you can enroll starting three months before the month you turn 65. You cannot enroll earlier than that, even if you want to.

What happens if I miss the important date to enroll?

You can still enroll, but you will pay a permanent penalty on Part B and Part D premiums. The penalty is roughly 10 percent per year for Part B and 1 percent per month for Part D. The only exception is if you had employer or union coverage based on current work — then you have eight months after losing that coverage to enroll without penalty.

Do I have to enroll in Medicare if I have employer health insurance?

No, you can stay on your employer plan if it is based on your current work. However, you must notify Medicare that you have this coverage to avoid being charged a late-enrollment penalty later. Once you leave that job or lose the coverage, you have eight months to enroll in Medicare.

What is the difference between enrolling during my initial period and enrolling late?

Enrolling during your initial enrollment period (three months before to three months after you turn 65) means no penalty. Enrolling after that window closes means you pay a permanent penalty on your premiums. The only way to avoid the penalty after your initial period is if you had may have access to employer or union coverage.

Can I change my mind after I enroll in Medicare?

Yes, but only during certain windows. You can switch between Original Medicare and Medicare Advantage during the annual open enrollment period (October 15 to December 7) or the Medicare Advantage open enrollment period (January 1 to March 31). Outside these windows, changes are limited unless you have a may have access to life event.