Coinsurance is the percentage of a medical bill you pay after your insurance company pays its share
When you have coinsurance, you and your insurance company split the cost of a covered service. Your insurance pays a percentage, and you pay the rest. For example, if your plan has 20% coinsurance for a doctor visit that costs $100, your insurance pays $80 and you pay $20. The percentage stays the same whether the bill is $50 or $500—you always pay your percentage of whatever the actual charge is.
Coinsurance is different from a copay, which is a flat dollar amount you pay each time you use a service. It is also different from a deductible, which is the amount you must pay out of pocket before your insurance starts paying anything at all. Once you have met your deductible, coinsurance kicks in, and both you and your insurer share the cost going forward.
Coinsurance applies to many types of care: hospital stays, specialist visits, imaging like MRIs, and surgeries. Your insurance card or plan documents will list what percentage coinsurance applies to each type of service. Some services may have no coinsurance (your insurance covers 100%), while others might be 10%, 20%, or higher.
Key Takeaways
- Coinsurance is a percentage of the bill you pay after your deductible is met, while your insurance pays the remaining percentage.
- The percentage does not change based on the bill amount—if your plan has 20% coinsurance, you pay 20% whether the service costs $100 or $1,000.
- Coinsurance applies to many services including hospital care, specialist visits, and procedures, but the percentage varies by service type in your plan.
- Your out-of-pocket maximum is the most you will pay in coinsurance and deductibles combined in a year; once you reach it, your insurance covers 100% of remaining covered services.
How coinsurance works with your deductible and out-of-pocket maximum
Your deductible comes first. Until you pay this amount out of pocket, your insurance does not pay anything. Once your deductible is met, coinsurance begins. From that point forward, you and your insurance split every bill according to your coinsurance percentage.
Your out-of-pocket maximum is a cap on how much you will pay in total during a calendar year. This includes your deductible, coinsurance, and copays. Once you reach this maximum, your insurance covers 100% of all remaining covered services for the rest of that year. For example, if your out-of-pocket maximum is $5,000 and you have already paid $4,800 in deductible and coinsurance, you only need to pay $200 more before your insurance covers everything else at no cost to you.
The order matters: you pay your deductible first, then coinsurance applies to subsequent bills, and the total of all your out-of-pocket payments counts toward your maximum. Once you hit the maximum, coinsurance stops applying because your insurance takes over completely.
Coinsurance on common medical services
Different services often have different coinsurance percentages. A primary care visit might be 20% coinsurance, while a specialist visit could be 30%. Hospital inpatient care might be 15% coinsurance, and outpatient surgery could be 20%. Your plan documents will list the coinsurance for each category of service.
Some services may have no coinsurance at all. Preventive care—like annual physicals, certain screenings, and vaccinations—is often covered at 100% by law, meaning you pay nothing once your deductible is met. Emergency room visits might have a flat copay instead of coinsurance, or they might have coinsurance that applies after the copay.
Mental health services, physical therapy, and prescription drugs may each have their own coinsurance rates. Always check your plan documents or call your insurance company before a service to confirm what percentage you will owe. The bill you receive from the provider may not match what you actually have to pay after insurance processes it.
What happens when you receive a coinsurance bill
After you receive medical care, the provider sends a bill to your insurance company. Your insurance processes the claim and determines what it will pay based on your plan's negotiated rate for that service. The insurance company then sends you an Explanation of Benefits (EOB), which shows what the provider charged, what your insurance paid, and what you owe.
The amount you owe on the EOB is your coinsurance. The provider may bill you directly for this amount, or your insurance company may send you a bill. Either way, you are responsible for paying it. If you do not pay, the provider can send the bill to collections, which will damage your credit score.
If the bill seems wrong, compare it to your EOB. Check that the service listed matches what you received, that the date is correct, and that the coinsurance percentage matches your plan. If something does not match, contact your insurance company or the provider's billing department to ask for a correction.
How to estimate your coinsurance costs before treatment
Before you schedule a service, call your insurance company or log into your online account to find out the coinsurance percentage for that type of care. Then ask the provider's office for an estimate of what the service will cost. Multiply the estimate by your coinsurance percentage to get a rough idea of what you will owe.
Keep in mind that this is an estimate only. The actual bill may be higher or lower depending on what the provider finds during the service. For example, if you are having surgery, the surgeon may discover additional work that needs to be done, which will increase the total bill and your coinsurance.
Also check how much of your deductible you have already met this year. If you have not met it yet, you will pay the full amount of the bill up to your deductible, and then coinsurance will apply to any amount above that. Once you know your deductible status and the coinsurance percentage, you can calculate a more accurate estimate of your out-of-pocket cost.
Coinsurance versus copays and deductibles
| Payment Type | What You Pay | When It Applies |
|---|---|---|
| Copay | A fixed dollar amount (e.g., $25) | At the time of service, usually for office visits or urgent care |
| Deductible | A set amount you must pay before insurance pays anything (e.g., $1,500) | First, before any other cost-sharing |
| Coinsurance | A percentage of the bill (e.g., 20%) | After your deductible is met, for covered services |
A copay is simpler to predict because it is always the same amount. A $25 copay for a doctor visit is $25 whether the visit costs $50 or $200. Coinsurance, by contrast, changes with the bill amount. If your coinsurance is 20% and the bill is $500, you pay $100. If the bill is $1,000, you pay $200.
Some plans use copays for routine visits and coinsurance for more expensive services like hospital stays or surgery. Others use coinsurance for most services. Your plan documents will specify which applies to each type of care.
Frequently Asked Questions
Does coinsurance count toward my out-of-pocket maximum?
Yes. Every dollar you pay in coinsurance counts toward your out-of-pocket maximum. Once you reach that maximum, your insurance covers 100% of remaining covered services for the rest of the year. Your deductible and copays also count toward this maximum.
What if I do not pay my coinsurance bill?
The provider can send the unpaid bill to a collections agency, which will report it to credit bureaus and damage your credit score. You may also receive calls or letters from the provider or a debt collector. It is better to contact the provider's billing department to discuss a payment plan if you cannot pay the full amount at once.
Can coinsurance change during the year?
No. Your coinsurance percentage is set when your plan year begins and does not change until the next plan year starts. However, if you switch insurance plans mid-year, your new plan may have different coinsurance percentages. Your out-of-pocket maximum also resets each January (or whenever your plan year begins).
Why does my coinsurance bill not match the provider's original bill?
Your insurance company negotiates rates with providers, so the amount your insurance pays is based on the negotiated rate, not the provider's full charge. You pay coinsurance on the negotiated rate, not the original bill. This is why your coinsurance bill is often much lower than the provider's initial invoice.
Do I pay coinsurance for preventive care?
No. Preventive services like annual physicals, certain screenings, and vaccinations are covered at 100% by law, even if you have not met your deductible. You pay nothing for these services. However, if the visit includes treatment for a health problem, that treatment portion may have coinsurance.