Dear Liz: I have a question after reading your column about avoiding costly Medicare mistakes. My husband and I have both reached 65 this past year. We both signed up for Medicare Part A hospital coverage, which is free. I retired two years ago, but am covered by my husband’s employer’s health insurance. I’m now confused about whether I should have signed up for Medicare Part B, which covers doctors visits but requires monthly premiums. His employer explained to him that he would avoid penalties if he signed up for Part B within eight months of his retirement, but no one has mentioned his wife.

Answer: You’re covered under the same rules. As long as your spouse is still working and you’re covered by that employer’s health insurance, you don’t have to sign up for Medicare Part B. But, as your husband’s employer noted, when that employment ends you both should enroll in Part B within eight months to avoid future penalties.