How do I find the lowest total drug cost, not just the lowest premium?

The premium is the part of a drug plan's cost that shows up most obviously, but it's rarely the whole story. Two plans with very different premiums can flip completely once you factor in the deductible, the tier placement of your specific drugs, and whether your preferred pharmacy is in-network or preferred.Medicare's Plan Finder at Medicare.gov is built exactly for this. When you enter your medications, including dosages and how often you take them, it calculates an estimated annual cost for each plan that includes the premium, the deductible, and your expected copays or coinsurance at the pharmacy. That total cost number is far more useful than the monthly premium alone.A few things to watch closely. First, check which pharmacy you'd use. Many plans charge less at preferred pharmacies, sometimes significantly less. Second, look at how each plan places your drugs on its formulary. A formulary is the plan's list of covered drugs and what you'll pay for each one. A drug on a higher tier costs more out of pocket. Third, consider whether any of your drugs require prior authorization or step therapy, which means the plan may require you to try a cheaper drug first.Plan details change every year, so it's worth reviewing your coverage during Medicare's Open Enrollment Period, which runs October 15 through December 7 each year.