How do I sign up for Original Medicare (Part A and Part B)?
You sign up for Medicare (Part A and Part B) through the Social Security Office. You can complete your enrollment online at socialsecurity.gov, by calling Social Security at 1-800-772-1213 or by visiting your local Social Security office in person.
Medicare Part A late enrollment penalty
A 10% late enrollment penalty is applied to your monthly premium for twice the number of years you did not have Part A despite being eligible.
Example:
If you were eligible for Part A for 2 years but didn't sign up, you'll have to pay the higher premium for 4 years. Usually, you don't have to pay a penalty if you meet certain conditions that allow you to sign up for Part A during a special enrollment period.
Medicare Part B late enrollment penalty
A 10% late enrollment penalty is applied to your monthly premium for twice the number of years you did not have Part B despite being eligible.
Example:
Your Initial Enrollment Period ended December 2016. You waited to sign up for Part B until March 2019 during the General Enrollment Period. Your coverage starts July 1, 2019. Your Part B premium penalty is 20% of the standard premium, and you’ll have to pay this penalty for as long as you have Part B. (Even though you weren't covered a total of 27 months, this included only 2 full 12-month periods.)