Health insurance comes with its own vocabulary, and few terms trip people up more than coinsurance. It sounds like it might mean the same thing as a copay, but the two work very differently — and mixing them up can lead to surprise medical bills.
Here’s a plain-English breakdown of what coinsurance is, how it compares to copays, and what it means for your wallet.
What Is Coinsurance?
Coinsurance is the percentage of a covered medical expense you pay after you’ve met your deductible. It’s always expressed as a split between you and your insurer — for example, 80/20 means the plan pays 80% and you pay 20%.
A few important details:
- Coinsurance only kicks in after you’ve satisfied your deductible for the year.
- It applies to covered services. If a service isn’t covered by your plan, you’re responsible for the full cost regardless.
- Your coinsurance payments count toward your out-of-pocket maximum. Once you hit that cap, your insurer pays 100% of covered services for the rest of the year.
You can find your plan’s specific coinsurance percentage in your benefits booklet or by contacting your insurer directly.
How Does Coinsurance Work?
The most common arrangement in health insurance plans is an 80/20 split: your insurer covers 80% of covered medical costs and you cover 20%, after your deductible is met.
A Step-by-Step Example
Say your health plan has:
- An annual deductible of $1,000
- An 80/20 coinsurance split
- An out-of-pocket maximum of $5,000
You need surgery that costs $5,500.
- You haven’t met your deductible yet, so you first pay $1,000 out of pocket.
- The remaining $4,500 is subject to coinsurance. You owe 20% of that: $900.
- Your insurer covers the remaining 80%: $3,600.
- Your total cost for this procedure: $1,900 ($1,000 deductible + $900 coinsurance).
How a $5,500 surgery bill gets divided
Now your out-of-pocket total for the year stands at $1,900. Your deductible is satisfied. If you need another procedure later in the year, you skip straight to the 80/20 split — no more deductible. And once your cumulative out-of-pocket spending reaches $5,000, the plan pays 100% for the rest of the year.
What’s the Difference Between Coinsurance and Copay?
Both coinsurance and copays are forms of cost-sharing — ways that insurers spread medical costs between themselves and policyholders. But they work differently.
Deductibles
A deductible is the fixed amount you must pay each year before your plan begins sharing costs. For example, with a $3,000 deductible, you pay the first $3,000 in covered expenses yourself. Only then does coinsurance (or in some plans, the plan’s full coverage) kick in.
Families often have both individual and family deductibles — once the family deductible is met, no additional family member needs to satisfy their individual deductible for that year.
Copays
A copay is a fixed dollar amount you pay for a specific type of service — regardless of what the total bill is and regardless of whether you’ve met your deductible.
Common copay examples:
- $25 for a primary care visit
- $50 for a specialist
- $10–$40 for a prescription refill
- $150–$250 for an emergency room visit
Copays typically do not count toward your deductible, but they do count toward your out-of-pocket maximum (depending on your plan).
Coinsurance vs. Copay: Key Differences
| Copay | Coinsurance | |
|---|---|---|
| Format | Fixed dollar amount | Percentage of the bill |
| When it applies | At time of service (often before deductible is met) | After your deductible is satisfied |
| Predictability | Easy to know in advance | Depends on the total cost of care |
| Example | $30 per specialist visit | You pay 20% of a $500 procedure = $100 |
In practice, many plans use both: you might pay a copay for routine office visits and prescription drugs, and then coinsurance for hospitalizations or procedures.
Does Property Insurance Have Coinsurance?
Yes — the term also appears in property insurance, though it works differently than in health coverage.
A coinsurance clause in a property insurance policy requires you to insure your home or building at a minimum percentage of its replacement value — commonly 80%. If your property is underinsured relative to that threshold, your insurer can impose a coinsurance penalty on any claim you file, reducing your payout proportionally.
For example, if your home has a replacement value of $200,000 and your policy requires 80% coinsurance coverage, you need at least $160,000 in coverage. Carrying less than that exposes you to a penalty if you file a claim.
Some policies allow you to add a waiver of coinsurance, which removes this requirement — particularly relevant for small claims or total-loss situations.
Educational note: This article is for informational purposes only. It is not personalized insurance or financial advice. Coverage terms vary by plan and insurer — review your policy documents or speak with a licensed agent for guidance specific to your situation.
The Bottom Line
Coinsurance is the percentage of a covered medical bill you share with your insurer after meeting your deductible. A copay is a flat fee paid at the time of service. Both count toward your annual out-of-pocket maximum.
When comparing health plans, look at the full picture: premium, deductible, coinsurance percentage, copay amounts, and out-of-pocket maximum. A plan with a lower premium but higher coinsurance may cost more if you use a lot of medical services during the year.