• Signing up for Medicare Part B when you are first eligible (such as when you turn 65) makes sure that you have coverage when you need it.


• Most people who do not sign up for Part B when first eligible can only enroll between January 1 and March 31 each year, with coverage starting the month after you enroll.


• This may cause a gap in your coverage and you may have to pay a lifetime late enrollment penalty.


• The penalty is added to your monthly premium and it increases the longer you wait. Your monthly premium will go up 10 percent for each 12-month period you were eligible for Part B but did not sign up for it.


• If you are still working, you may have a chance to sign up for Medicare Part B without a penalty during a limited "Special Enrollment Period."