The five numbers that decide what you pay

1. Premium

What you pay every month just to have insurance, whether or not you use it. Paying the premium doesn't count toward your deductible.

2. Deductible

The amount you pay for covered care each plan year before the plan starts sharing costs. Many plans cover preventive care and some visits (with a copay) before you meet the deductible.

Deductible $2,000. Your first bill is $1,500, so you pay all $1,500. Your next bill is $1,000: you pay $500 to finish the deductible, then cost-sharing kicks in for the rest.

3. Copay

A flat fee for a service, such as $30 for a doctor visit or $10 for a generic drug.

4. Coinsurance

Your percentage share of a bill after the deductible. With 20% coinsurance, you pay 20% and the plan pays 80%.

$5,000 covered bill after the deductible is met, 20% coinsurance: you pay $1,000 and the plan pays $4,000.

5. Out-of-pocket maximum

The most you'll pay for covered in-network care in a plan year, counting deductible, copays and coinsurance (premiums aren't included). Once you hit it, the plan pays 100% of covered in-network care for the rest of the year. The federal government sets the highest out-of-pocket maximum allowed each year for ACA plans; see HealthCare.gov.

Your true yearly cost

Total cost = (monthly premium × 12) + what you pay for care, and the second part is capped at the out-of-pocket max. A low premium isn't always cheaper. See the worked examples.

Other terms

Network: the doctors, hospitals and pharmacies contracted with the plan.
Formulary: the plan's list of covered drugs.
Prior authorization: approval the plan requires before certain care.
SBC: Summary of Benefits and Coverage, a standard comparison document every plan must provide.