Compare the total, not the premium

The cheapest Medicare plan on paper is often not the cheapest plan to live with. The premium is one number among several.

Three checks matter more than the monthly price.

Start with the drug list. Every Medicare Advantage and Part D plan publishes a formulary, and it can change every January. A medication covered this year may be dropped, moved to a costlier tier, or made subject to prior authorization. The Plan Finder at medicare.gov accepts a list of prescriptions and returns each plan's projected cost for the year, which is the number worth comparing.

Next, the pharmacy. Plans sort pharmacies into preferred and standard networks, and the same prescription can cost noticeably more at a standard pharmacy. A plan that looks cheap can turn expensive at the drugstore across the street.

Then the doctors. Medicare Advantage plans work through networks, and networks are rebuilt every year. A physician in the plan this year may be out of it in January, and confirming that means calling the plan or the office rather than trusting a printed directory.

Every state runs a free counseling service, the State Health Insurance Assistance Program, whose counselors work on no commission and sell nothing.

The plan must receive an enrollment request by December 7. A request sent December 8 is a request for the following year.