You’ll need the CMS-40B form if you already have Medicare Part A and need to enroll in Part B.
What you’ll need:
• Your social security number, current address, and phone number
• You signature on the form
When you can use this form:
• You’re signing up for Part B during your Initial Enrollment Period (IEP) when you’re first eligible for Medicare.
• During the General Enrollment Period (GEP). This period is January 1 – March 31 each year.
• During a Special Enrollment Period (SEP) if you qualify (such as if you had insurance through an employer.