What Is Coinsurance in Health Insurance?
Coinsurance is the percentage of covered costs you pay after your deductible, until you reach your out-of-pocket maximum. Here's an example and how it differs from a copay.
Quick answer
Coinsurance is your percentage share of covered costs after you meet the deductible, such as 20%. The plan pays the rest. You keep paying coinsurance until you reach the out-of-pocket maximum.
An example
A hypothetical plan: $1,000 deductible, 20% coinsurance, $5,000 out-of-pocket maximum. A $6,000 covered procedure, with the deductible not yet met:
Show the numbers behind this chart
| Amount | |
|---|---|
| Deductible (you) | $1,000 |
| Coinsurance (you) | $1,000 |
| Plan | $4,000 |
Coinsurance vs. copay
| Coinsurance | Copay | |
|---|---|---|
| Form | A percentage | A flat dollar amount |
| When it applies | Usually after the deductible | Often regardless of deductible, depending on the plan |
| Cost predictability | Depends on the bill | Known in advance |
Medicare
Original Medicare Part B generally charges 20% coinsurance after the deductible, with no out-of-pocket maximum, which is why many people add Medigap or choose Medicare Advantage; see Medigap vs. Medicare Advantage.
See also deductibles, coinsurance, and out-of-pocket maximums.
The takeaway
Coinsurance is a percentage you pay after the deductible. Combined with the out-of-pocket maximum, it determines your cost for larger medical bills.
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