I'm 65 and have been denied Medicare because my husband is five years younger. Help!

Q. I turned 65 in August and my husband is 60. I've been a homemaker and have never paid into Social Security. My husband is retired and will take Social Security when he's 62. I currently buy health insurance on the open market and he gets his health care from the VA. My local Social Security office told me I'm not eligible for Medicare until my husband starts drawing Social Security. Will I be charged a penalty for Parts B and D because I didn't enroll at 65?

A. Wow, lots to sort out here.

First of all, the Social Security office misinformed you about your Medicare eligibility. You not only are entitled to sign up for Medicare now, you must do it promptly or you will miss your initial enrollment period, which concludes at the end of the third month after your birthday month—for you, the end of November. And you're right to be concerned about penalties for late enrollment for Part B. If you don't sign up now, you will be assessed a permanent premium surcharge of 10 percent for every year you should have been on Part B but weren't.

According to a Medicare spokeswoman I contacted, because you don't have any Social Security credits in your own name, you will have to pay a premium of $248 a month for Part A until your husband starts taking Social Security benefits, at which point it will become free. You will also have to pay the regular premium for Part B, which by the time your coverage starts in early 2012 will be $99.90 a month. Everyone on Medicare pays this.

Most Part D plans run $30 to $35. That's under $400 a month for the whole package. Adding a Medigap plan to pick up your Part A and B deductibles and coinsurance might run you another $100 to $200 a month, depending on which type of plan you choose.

Your other choice would be to sign up for Parts A and B, then obtain your coverage through a private Medicare Advantage plan. Many of these plans charge no additional premium beyond what you are already paying Medicare, and most include Part D coverage as well. Just be aware they are managed care plans that come with various deductibles and co-pays. Here's more information about how Medicare Advantage works.

You didn't say how much your private insurance costs, but at your age, it's likely to be either very expensive or saddled with a high deductible, or both. Your Medicare package of benefits may be cheaper—even more so in two years when your Part A premium drops to zero.

If, on the other hand, you somehow have inexpensive private coverage and want to keep it, you can defer signing up for Part A until your husband goes on Social Security, but you should still sign up for Part B to avoid that penalty. Bonnie Burns, a Medicare expert with California Health Advocates, a nonprofit consumer group, says that if you stay on your private insurance, you should check with your carrier, as well as your state's insurance department, to see how your benefits will coordinate with your Part B coverage.

As for Part D, you'll need to find out from your carrier whether your private prescription coverage is equivalent to Part D coverage (so-called "creditable" coverage). If it is, you can postpone signing up Part D until you drop your private plan. If it's not, you must take Part D now or face a late signup penalty, a 1 percent premium surcharge for every month you could have been on Part D but weren't.

Got another question for me? Ask it here. And see our advice on buying and using health insurance.

—Nancy Metcalf