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12 Essential Medicare Deadlines and Timetables You Can’t Afford to Miss

How the calendar can shape your coverage — and your potential penalties

7.5-minute read

Article 6 out of 14 in Medicare Basics

Linda Dono,

AARP

Reviewed by

Xavier Vaughn, MPH

Published February 25, 2026

illustration of a person holding an umbrella, where the canopy of the umbrella is a large blue and white desk calendar with a red date highlighted.

Kiersten Essenpreis

Key takeaways

More people must decide when to enroll in Medicare nowadays.
Pitfalls abound. COBRA, relocation rules have short triggers.
Know the rules for enrolling in Part D and Medigap.
Part B has a penalty if you don’t sign up on time.
Unless you qualify with a disability, Medicare is for 65+.

For various reasons, more and more Americans are delaying their Social Security benefits until after age 65.

That means fewer people eligible for Medicare are being automatically enrolled in the federal health insurance program. Fifteen years ago, about 70 percent of people who filed for Social Security were mailed their Medicare card without having to complete any extra steps; today it’s 40 percent.

The good news: The closer you get to full retirement age, 67 for those born in 1960 and later, before filing for Social Security, the higher your monthly retirement benefits. And for each year from age 67 until age 70 that you wait to file, you get about 8 percent more money, 24 percent more in total.

You also get more control over when to start parts of your Medicare health care coverage.

For example, you can sign up immediately for Part A at age 65 — free for anyone or their spouse who has paid 40 quarters of Medicare taxes over their lifetime of work — as a backup to hospitalization coverage from your job. And generally, if you’re at a company with 20 or more workers and as long as you or your spouse is employed, you can continue with your usual insurance instead of paying a monthly premium to the federal government for Part B.

But you also might become more confused as you look at stopping your medical insurance at work and transitioning to Medicare.

Many of Medicare’s deadlines don’t start on fixed calendar dates — and sometimes carry penalties — but instead are tied to when you stop work, move or apply for Medicare. Here are some key numbers to know as you reach 65 or work beyond that age.

1. Zero days

If you’ve already stopped working and are continuing your employer’s health care coverage through COBRA (which stands for the federal Consolidated Omnibus Budget Reconciliation Act of 1985), your benefits usually end at age 65, no matter how many months of COBRA coverage you were offered.

The scenarios get more complicated if you become eligible for COBRA benefits after 65. But the simplest answer is to make sure that you or your spouse has health insurance from a job at which you’re actively working, or sign up for Medicare.

Otherwise, you could face a coverage gap that leaves you paying for the lion’s share of your medical bills if you’re hospitalized or have extensive doctors’ appointments.

2. 54 days

Medicare’s open enrollment period runs Oct. 15 to Dec. 7 every year. That’s when you can buy or switch Part D or Medicare Advantage plans, available from private insurers after you’ve signed up initially.

If you choose to do nothing, the coverage you already have will continue, but what the plan offers may change. Your doctors could leave your Medicare Advantage plan, or your drug plan could alter its medication list, dropping prescriptions you take or moving them to a higher price tier.

3. 2 months

If you move beyond the coverage area of your Part D or Medicare Advantage plan, you’ll have two months after the relocation to change to a policy that covers your area. If your old Medicare Advantage plan drops you because of your change of address, you’ll be enrolled in original Medicare if you don’t decide during this time.

You’ll get the same two-month period to choose or switch Part D or Medicare Advantage plans if you return to the U.S. after living abroad, are released from incarceration or move out of a nursing home or rehab center.

4. 63 days

To avoid a penalty, you have 63 days to enroll in a Medicare Part D prescription plan or Medicare Advantage plan with drug coverage after you apply for Part A or Part B. But since it’s easier to count months than days, consider it two months.

Sixty-three days is also the amount of time you have to enroll in a Medicare Part D prescription plan or a Medicare Advantage plan with drug coverage after you lose drug coverage considered at least as good as Part D, called “creditable coverage,” from an employer, a retiree plan, Tricare or another source.

5. 3 months

The Medicare Advantage open enrollment period runs Jan. 1 to March 31 each year. Medicare Advantage members can change plans or transition to original Medicare and join a stand-alone Part D plan; coverage begins the following month.

Jan. 1 to March 31 is also Medicare’s general enrollment period for beneficiaries who qualify for Medicare but did not sign up for Part A or Part B during their initial enrollment period or any subsequent special enrollment periods for which they qualified.

If you lose Medicaid or Extra Help eligibility, you’ll have three months from the date you’re no longer eligible or the date you were notified of ineligibility, whichever is later, to decide on Medicare coverage that meets your health and financial needs: original Medicare and a Part D prescription plan or a Medicare Advantage policy with drug coverage.

6. 6 months

Your once-in-a-lifetime Medigap open enrollment period, which begins the month your Medicare Part B plan is in force, lasts six months. During this time, you can buy any private Medicare supplement policy, a.k.a. Medigap, in your area for the best rates for your age. This is called a guaranteed issue right.

Medigap policies provide important financial protections for those on original Medicare because original Medicare has no limit on out-of-pocket spending. This private insurance doesn’t have the same restrictions on purchase as Part D — you can buy a policy at any time — but you could be subject to coverage delays, higher premiums or outright rejection for preexisting conditions outside of Medigap open enrollment.

7. 7 months

Medicare’s initial enrollment period includes the three full months before your 65th-birthday month, your birthday month and the three months after. If you were born on the first of a month, everything happens one month earlier.

If you haven’t worked a total of 40 quarters (essentially 10 years) before you turn 65, don’t have health insurance through your employer or spouse, or don’t get financial help through Medicaid or a Medicare Savings Program, you could face a penalty if you don’t sign up for Medicare Part A during your initial enrollment period.

8. 8 months

Retirees who have lost private health insurance through a group plan from a job or their spouse’s job must sign up for Medicare Part B within this period or face a lifelong late enrollment penalty.

9. 24 months

People younger than 65 can become eligible for Medicare after receiving Social Security Disability Insurance (SSDI) payments for 24 months. For those who don’t have amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, or kidney failure, also called end-stage renal disease, the clock starts when the Social Security Administration says you became eligible for SSDI, so it takes into account retroactive payments that preceded the date your claim was approved.

ALS and kidney failure can be fast moving. If you have either disease, you’ll immediately be eligible for Medicare when you’re approved for SSDI.

Be aware: Qualifying for Medicare before age 65 will not start your federally mandated six-month Medigap open enrollment period. That starts in your 65th-birthday month. But more than half of the states have laws requiring insurers to sell at least one Medigap policy to younger Medicare beneficiaries.

10. 65 years

This is the earliest age a person who has paid 10 years of FICA taxes and is not disabled can sign up for Medicare health insurance. Your birthday month is at the center of a seven-month initial enrollment period.

11. 67 years

A 65-year-old today who has paid at least 10 years of Social Security taxes will be eligible for 100 percent of retirement benefits at 67. That’s when many people may retire and decide to sign up for Medicare Part B if their employer had been providing health coverage.

12. 70 years

If you’re still working, you can accrue additional Social Security retirement income until age 70 and get the biggest monthly benefit possible when you file. You can continue with your employer’s health plan and save money on a Part B premium as long as you or your spouse work and are eligible for coverage.

The private insurer’s plan may have better benefits, especially for dental, hearing and vision, than your options under Medicare. But you have the luxury of choice, so choose the best alternative for your needs.

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About the author

Linda Dono is a senior executive editor for AARP. Previously, she served as a reporter and editor for USA Today, Gannett News Service and newspapers in four states, including The Cincinnati Enquirer.

About the reviewer

Xavier Vaughn, an AARP adviser for Medicare programs, previously worked at the National Council on Aging in Arlington, Virginia, and the Primaris Foundation, based in Columbia, Missouri. He earned his master’s degree in public health from the University of Alabama at Birmingham.