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Every plan that covers prescription drugs keeps a formulary, a list of covered medicines grouped into tiers. The tier decides what you pay. Two plans can cover the same drug and charge completely different amounts for it.
How tiers are usually arranged
Lower tiers hold generic medicines and usually carry the smallest copays. Middle tiers hold preferred brand name drugs. Higher tiers hold non-preferred brands and specialty medicines, and those often use coinsurance instead of a flat copay, so you pay a percentage of a large price. The exact layout varies by plan, which is why the formulary deserves a look before you enroll, not after your first pharmacy visit of the year.
Rules that ride along with tiers
Some medicines need prior authorization, where the plan wants documentation before it pays. Some have step therapy rules, where you try a lower cost option first. Some have quantity limits. None of these appear in the premium or deductible, and all of them affect what a year on the plan actually feels like. If a medicine matters to your health, search the formulary for its name and read the notes next to it.
Where drug costs meet the rest of the plan
On many marketplace plans, drug copays for lower tiers apply before the deductible, while higher tier drugs may sit behind it. What you pay for covered drugs counts toward your out-of-pocket maximum, which our out-of-pocket maximum explainer covers. When two plans look close on medical costs, the one that tiers your regular medicines lower often wins the year. That trade shows up clearly in tier comparisons like Gold vs Silver health plans.
If your drug is not covered
Ask your doctor whether a covered alternative in the same class works for you. If not, plans have a formulary exception process. You can also compare the cash price with discount programs against your plan copay, though money spent outside the plan usually does not count toward your deductible or maximum. Finally, check cost-sharing reductions if you buy through the marketplace, since lower cost sharing can change drug costs on Silver plans.
