What Is Coinsurance?
Coinsurance is your share of the cost of a covered healthcare service, calculated as a percentage. After you've met your deductible, you and your insurance split the cost. Common splits are 80/20 (insurance pays 80%, you pay 20%) or 70/30.
How Coinsurance Works: Real Example
You've already met your $2,000 deductible. You need a $10,000 surgery. With 80/20 coinsurance:
- Insurance pays: $8,000 (80%)
- You pay: $2,000 (20%)
Your total out-of-pocket for the year: $2,000 deductible + $2,000 coinsurance = $4,000. This is well under the out-of-pocket maximum of $10,600, so you'd continue paying 20% coinsurance on future services until you hit that cap.
Coinsurance by Metal Tier
- Bronze: Typically 40% coinsurance (you pay 40%, plan pays 60%)
- Silver: Typically 30% coinsurance (you pay 30%, plan pays 70%)
- Gold: Typically 20% coinsurance (you pay 20%, plan pays 80%)
- Platinum: Typically 10% coinsurance (you pay 10%, plan pays 90%)
These percentages apply to both ACA marketplace plans and private ACA-compliant plans.
Key difference from copays: Coinsurance is unpredictable because it's based on the total bill. A 20% coinsurance on a $500 bill is $100, but 20% on a $50,000 hospital stay is $10,000. That's why the out-of-pocket maximum exists — to cap your total exposure.
When Does Coinsurance Apply?
Coinsurance kicks in after you meet your deductible. Before that, you pay 100% of covered services (except preventive care, which is always $0). Once you hit your out-of-pocket maximum, coinsurance drops to 0% — insurance pays 100% for the rest of the year.
Related Terms
Last updated: March 30, 2026.
