You have three months before your 65^th birthday, the month of your 65^th birthday, and three months after your 65^th birthday to apply for Social Security benefits of any kind, including Medicare.

If you do not apply during this time, you can only apply during an open enrollment period, generally in January of each year.

The only exception to these rules is if you are covered by a group medical plan of an employer. In this case, you may apply to Social Security during a 7-month period beginning with the earlier of:

• The month employment ends.
• The month group coverage ends.

While you must apply to get benefits, Medicare Part A is free. Medicare Part B has a monthly premium cost, which historically has been increased each year.

If you fail to apply for Social Security benefits during the period of time surrounding your 65^th birthday (or end of group coverage), there is a 10% penalty on the amount of the Medicare Part B premium each year that you do not apply for Social Security benefits.

Normally, the cost of Medicare Part B is taken from the Social Security check. However, for people who are earning too much money from employment to collect regular Social Security benefits, the premium must be paid directly.

Source: Guide to Social Security and Medicare