If you are still working for an employer of 20 or more employees, you can notify Social Security (1-800-772-1213) that you don’t want Part B at this time because you are still working. (If your company is under 20 employees, they can ask you to go onto Medicare.) Social Security will re-issue your Medicare card showing only your Part A benefit.
When you do want to activate your Part B (outpatient) benefit, you will need to submit 2 forms to Social Security; one form you complete and the 2nd form is completed by your employer. These forms will indicate the date you will lose your employer coverage. Both forms will need to be submitted to Social Security to activate your Part B without any penalty.