In most cases, if you don't sign up for Part B when you're first eligible, you'll have to pay a late enrollment penalty. You'll have to pay this penalty for as long as you have Part B. Your monthly premium for Part B may go up 10% for each full 12-month period that you could have had Part B, but didn't sign up for it. Also, you may have to wait until the General Enrollment Period (from January 1 to March 31) to enroll in Part B. Coverage will start July 1 of that year.
Usually, you don't pay a late enrollment penalty if you meet certain conditions that allow you to sign up for Part B during a Special Enrollment Period.
If you have limited income and resources, your state may help you pay for Part A, and/or Part B. You may also qualify for Extra Help to pay for your Medicare prescription drug coverage.
Your Initial Enrollment Period ended September 30, 2009. You waited to sign up for Part B until the General Enrollment Period in March 2012. Your Part B premium penalty is 20%. (While you waited a total of 30 months to sign up, this included only 2 full 12-month periods.) You’ll have to pay this penalty for as long as you have Part B.