The rules for how much a plan pays can be complicated, so you may need to compare plans carefully. The figures here are for 2009.

• Deductible: With most plans, the covered individual pays out-of-pocket for the first $295 of his prescription drug costs for the year. A few plans that charge a high monthly premium waive some or all of this deductible.
• Partial coverage: After the deductible is reached, a plan pays 75 percent of costs for drugs covered in the plan's formulary. The individual is responsible for the other 25 percent. His portion comes in the form of a copayment for each prescription; the amount of the copayment may vary depending on the plan's drug tiers. This 75-25 split continues until each individual's total prescription drug costs for the year reach $2,700.
• No coverage (the "doughnut hole"): Once a person's total prescription drug costs for the year reaches $2,700 (combining what the plan pays and what the person pays), the plan pays nothing more for his drugs unless and until he reaches the catastrophic limit. A few high-premium plans pay some percentage of costs while he's in this expensive "doughnut hole."
• Catastrophic coverage: If the total amount a person pays out-of-pocket for prescription drugs during the year reaches $4,350, his plan will again begin coverage at the rate of 95 percent of further costs for covered drugs, with him paying the remaining 5 percent.