There are typically three different categories people fall into when joining Medicare. Knowing which one applies to you will help you avoid any delays in your start date.
The first scenario is for those who are already receiving Social Security benefits. Medicare Parts A & B will start automatically when you turn 65. Your card should arrive in the mail three months before your 65th birthday month. Enrollment can be verified by calling Social Security or by logging onto your Social Security account.
The second scenario is for those who are not receiving social security before age 65 but plan to start Medicare at age 65. You can sign up for Medicare starting three months before the month you turn 65. To do this you can either sign up online at https://www.ssa.gov/benefits/medicare/ or by phone at 1-800-772-1213.
The last scenario applies if you are over 65 and have chosen to delay Medicare because you had coverage through an employer. You can sign up for Medicare at https://secure.ssa.gov/.../medicare-part-b-online.../, and you will need to provide proof of creditable coverage. If you sign up online, you need to have the ability to photograph or upload documents providing proof of qualifying coverage. The other option is to fill out the Part B Enrollment Form (CMS-40B) and Request for Employment Information (CMS-L564) and fax or mail them to your local Social Security office or upload them on the Social Security website.