Another alternative is to enroll in both Parts A and B at the same time and consider Medicare as your secondary insurance, which would pay for any services not covered by your employer's health plan. There are federal regulations that come into play here if your company has fewer than 20 employees, so it's probably a good idea to talk to your employer's human resources department or plan administrator before making your decision.
WHAT YOU CAN EXPECT TO PAY FOR PREMIUMS
Premiums for new Medicare participants currently vary widely -- from $110.50 to $353.60 per month, depending on your income (the current ranges are $85,000 or less to above $214,000 for single filers; $170,000 or less to above $428,000 for married filing jointly). Therefore, your decision whether or not to enroll in Part B while you're still working might depend on how much money you're making. Also, note that your premium is based on your income two years prior to when you enroll. If you're making less now, it's possible that your most recent tax year can be used to calculate your premium if you meet certain criteria.
It's easy to get bogged down in all the details, but the most important thing is to stay on top of the dates and contact the Social Security Administration within your Initial Enrollment Period. In the meantime, there's plenty of very good information on the Medicare website (www.medicare.gov), including publications you can download and print for future reference. With the facts in hand, you can relax and enjoy some of the very real perks that come with getting older.