If you missed the opportunity to sign up for Medicare during your initial enrollment period (IEP) — and any special enrollment period you might be eligible for — you’ll need to enroll during the annual general enrollment period (GEP).

Some people delay signing up for Medicare because they have health insurance through their employer or their spouse’s employer. If you don’t enroll in Part B within eight months of losing your job-based health insurance, you can sign up only during the GEP.

The GEP runs Jan. 1 to March 31 each year. If you sign up during this time, your coverage will begin the first of the month after you sign up. Previously, you had to wait until July 1 for coverage to take effect after signing up during the GEP, but those rules changed in 2023.

If you’re eligible for premium-free Part A, you can enroll anytime by contacting the Social Security Administration (SSA) at 800-772-1213. If you’ve worked fewer than 40 quarters and don’t have a spouse (or an ex-spouse if you were married more than 10 years and haven’t remarried) who has paid Medicare taxes for 40 quarters or more, you’ll have to pay a premium for Part A and a penalty for signing up after your IEP or any special enrollment period (SEP) you might qualify for.
 

The SSA has no paper form available for enrollment in Part A during the GEP, so you must call. To sign up for Part B, complete Form CMS-40B and mail it to your local Social Security office or call for assistance. To find your local office, use the Social Security Field office locator.

Currently, SSA doesn’t offer an option to enroll online, so you may need to make other arrangements to during a general enrollment period.

Keep in mind: If you delayed signing up for Medicare because you or your spouse were working, you need to enroll within eight months of losing your health insurance; otherwise, you may have to pay a late enrollment penalty. This amounts to 10 percent of your Part B premium for each 12-month period you could have had Part B but didn’t enroll. If you had job-based coverage during that time, those months won’t count when the penalty is calculated.
 

To prove that you had health insurance, the employer who provided the insurance should fill out Form CMS-L564 and send it to the Social Security office along with your application.
 

Updated February 6, 2023