If you will be eligible for Social Security retirement benefits when you turn 65, you can enroll in Medicare at your local Social Security office, even if you are choosing to delay your Social Security retirement benefits. You can also enroll in Medicare by mailing a signed and dated letter to Social Security that includes your name, Social Security number, and the date you would like to be enrolled in Medicare, or by using the Social Security website at www.ssa.gov.

If you are receiving railroad retirement benefits or are eligible to receive railroad retirement benefits, enroll in Medicare by contacting your local Railroad Retirement Board field office.

It is very important that you keep proof of when you tried to enroll in Medicare, to protect yourself from incurring a Part B premium penalty if your application is lost. If you enroll through the mail, you should use certified mail and request a return receipt. If you go to the local Social Security office to enroll, take down the name of the person who helped you and ask for a written receipt. If you apply online, print out and save your confirmation page.