If you are going to keep working after you turn 65, but you are not eligible to stay on your group insurance, you can sign up for Parts A & B benefits which you can do 3 months prior to your birthday month and benefits start on the first day of your birthday month. After you have received your Medicare card, you will be ready to review and chose a Medicare Advantage, Prescription Drug and/or Medicare Supplement plan to cover the services Original Medicare does not. Original Medicare only covers 80% of agreed services and there is no cap on what the customer must pay out of pocket.