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Copay vs. Coinsurance: How Each Works and What You Pay

Senior comparing copay and coinsurance benefit details

A copay is a fixed dollar amount you pay for a covered service, such as $20 for a doctor visit. Coinsurance is a percentage of the cost of a covered service, such as 20% of the plan’s allowed amount. Both are your share of the bill, and which one you owe depends on the service, the plan and whether you have met your deductible. Below, we walk through each one with real numbers, show how they interact with deductibles and out-of-pocket maximums, and explain how they work in Medicare.

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TL;DR

A copay is a flat dollar amount per service. Coinsurance is a percentage of the allowed amount, so it rises with the cost of the care.
With 30% coinsurance you pay 30% and the plan pays 70%, usually after your deductible is met.
Meeting your deductible does not make care free. It starts the cost-sharing phase, where copays or coinsurance apply until you reach the out-of-pocket maximum.
Original Medicare Part B usually charges 20% coinsurance with no yearly out-of-pocket limit. Medicare Advantage plans use copays and coinsurance with a yearly cap that varies by plan.
Compare plans on expected total yearly cost, not on the premium or the copay amount alone.

Copay vs. coinsurance at a glance
What a copay is and how it works
What coinsurance is and how it works
A worked example with a deductible
Can you owe both a copay and coinsurance?
The out-of-pocket maximum: your safety net
How copays and coinsurance work in Medicare
Our perspective
Get help comparing your real costs
Common mistakes to avoid
FAQ
Sources

Copay vs. coinsurance at a glance

Copay Coinsurance What it is A fixed dollar amount A percentage of the allowed amount Example $20 per visit 20% of a $100 allowed amount, which is $20 Changes with the price of care? No Yes Usually applies At the time of service After the deductible, when the plan starts sharing costs Predictability High Lower, especially for big bills

The CMS uses exactly this comparison: a $20 copay versus 20% of a $100 allowed amount, which also comes to $20. The two look identical on a small bill. They split apart as the bill grows.

What a copay is and how it works

A copay (or copayment) is the flat fee your plan assigns to a specific service. Plans typically list different copays for different things: a primary care visit, a specialist visit, urgent care, an emergency room visit, a generic prescription, a brand-name prescription. You will find these on your plan’s summary of benefits.

The appeal is predictability. If your plan says $30 for a specialist, you know the number before you walk in, whether the provider’s allowed charge is $150 or $400. The tradeoff is that plans with low copays tend to charge higher premiums, and copays for expensive services such as hospital stays or imaging can be steep.

Two details trip people up:

Copays may or may not wait for the deductible. Some plans charge a copay from the first visit. Others make you pay the full allowed amount until the deductible is met, and only then switch to the copay.
A copay is not always the whole bill. It covers your share of the covered service. Non-covered services, out-of-network balance bills and premiums are separate. CMS’s Health Insurance Basics says cost sharing generally means deductibles, coinsurance and copayments, and does not include premiums, balance billing or non-covered services.

What coinsurance is and how it works

Coinsurance is your percentage share of the allowed amount for a covered service. HealthCare.gov defines it as the percentage of covered-service costs you pay after you have met your deductible, and its example is simple: with 20% coinsurance, you pay 20% and the insurer pays the rest.

“Allowed amount” matters. It is the price your plan has agreed to recognize for the service, which can be lower than what the provider first bills. Your percentage applies to that figure.

Does 30% coinsurance mean I pay 30% or 70%?

You pay 30%. The plan pays 70%. The Cornell Legal Information Institute describes it this way: with 30% coinsurance, the insured pays 30% of medical costs and the insurer pays 70%, once the deductible is reached.

The same logic answers the “is 100% or 80% coinsurance better?” question, with one catch. Plans express coinsurance from either side. Most health plans quote what you pay (20% coinsurance). Some policies, including certain dental and older indemnity plans, quote what the plan pays (80% coinsurance). Read the wording. If the document says the plan pays 80%, you owe 20%. CMS notes that when a plan describes coinsurance as what you pay, 80% means you pay 80% of the allowed amount, which is a far worse deal. A lower percentage you pay is better, all else equal.

A worked example with a deductible

The deductible is the third piece. It is the amount you pay for covered services each year before your plan starts sharing costs. Here is how all three work together, using HealthCare.gov’s own Marketplace example: a $1,500 deductible, 20% coinsurance and a $5,000 out-of-pocket maximum.

Before the deductible is met: a $125 office visit costs you the full $125.
After the deductible is met: the same visit costs you $25, which is 20% of $125.

CMS says the same thing in plain terms: if you have not met your deductible, you may owe the full allowed amount, or the remaining amount needed to meet the deductible, instead of just the coinsurance.

Now a bigger bill. HealthCare.gov’s coinsurance glossary illustrates $12,000 in allowable costs, a $3,000 deductible, 20% coinsurance and a $6,850 out-of-pocket maximum. You pay the $3,000 deductible, then 20% of the remaining $9,000, which is $1,800. Your total is $4,800, still below the maximum.

Swap in a flat copay and the picture changes. A plan that charges a $250 copay for an outpatient procedure costs you $250 whether the procedure’s allowed amount is $1,000 or $10,000. Coinsurance on the same procedure would cost you $200 or $2,000 at 20%. That is why copays feel safer on expensive care and coinsurance feels safer on cheap care.

Patient costs compared for copay and coinsurance

If I’ve met my deductible, why do I still pay coinsurance?

Because the deductible is a threshold, not a finish line. Once you cross it, the plan shares the cost with you. You keep paying your percentage or copay until you hit the out-of-pocket maximum. That is the point where the deductible stops being the story and the maximum takes over.

Can you owe both a copay and coinsurance?

Yes, on some plans and for some services. The clearest example is Original Medicare. According to Medicare.gov, outpatient hospital services generally mean 20% coinsurance for the doctor’s and other providers’ services, plus a copayment to the hospital for each service, with exceptions for certain preventive services. It is two charges for one trip, from two different parties.

The lesson: look at each line of the summary of benefits instead of assuming one rule covers the whole plan. A plan can use copays for office visits and prescriptions, and coinsurance for hospital stays, labs and imaging.

The out-of-pocket maximum: your safety net

The out-of-pocket maximum caps what you spend on covered services in a year. HealthCare.gov says that after you reach it, your plan pays 100% of covered services. Copays and coinsurance both count toward it on many plans, but check your plan documents, because some copays may not.

The cap has limits. CMS notes that premiums, balance bills and non-covered care can remain your responsibility after the maximum is reached. And HealthCare.gov advises comparing total expected yearly costs, meaning premiums, deductible, copays, coinsurance and the maximum, rather than choosing on premium alone.

How copays and coinsurance work in Medicare

If you are turning 65 or reviewing coverage, this is where the terms matter most, because the structure differs by type of Medicare.

Original Medicare (Parts A and B)

Per Medicare.gov’s 2026 costs page:

Part B has a $283 annual deductible, a $202.90 monthly premium, and usually 20% coinsurance for each Medicare-covered service after the deductible when the provider accepts assignment.
Part A has a $1,736 deductible per inpatient benefit period, plus daily hospital cost sharing that depends on how long you have been in the hospital during that benefit period.
There is no yearly out-of-pocket limit in Original Medicare unless you add supplemental coverage or join Medicare Advantage.

That last point is the big one. With 20% coinsurance and no cap, a large hospital or outpatient bill can produce a large share for you. Many people close that gap with a Medicare Supplement (Medigap) plan. If you want the Part A side explained, our article on avoiding multiple Part A deductibles in Colorado covers it, and our 2026 Medicare costs breakdown puts premiums, IRMAA and copays on one page.

Medicare Advantage

Medicare Advantage plans mix copays and coinsurance, and they carry a yearly out-of-pocket limit. Medicare.gov says costs and limits vary by plan. According to KFF’s 2026 analysis, the limit may not exceed $9,250 for in-network services, the average in-network limit is $5,421, and nearly one in five enrollees face in-network limits above $7,000. The same plan type can look cheap on premium and expensive when you actually need care, so the limit deserves as much attention as the copay for a doctor visit.

Typical copay structures show up in primary care, specialist visits and drugs, while inpatient stays and some outpatient services may use a per-day copay or a percentage. For a side-by-side look at how this compares with supplement coverage, see our guide to Medicare Advantage vs. Medigap.

Medicare Advantage — overview diagram

Which structure suits you?

There is no universally better option. Ask these questions:

How often do you see doctors? Frequent visits favor low flat copays.
Could you face a large bill? A hospital stay or surgery favors a low out-of-pocket maximum or a plan that fills Original Medicare’s 20% gap.
Do you take expensive drugs? Check whether your prescriptions have a copay or coinsurance by tier, and which tier each lands on.
Do you want predictable monthly costs? Copay-heavy plans are easier to budget.
Can you cover the deductible in cash? If not, a plan with copays from day one may feel safer.

Our perspective

Most of the confusion we see in Castle Pines and across Colorado is not about the definitions. People understand that a copay is flat and coinsurance is a percentage. The surprise comes later, when a bill arrives for a service they assumed had a $0 or $20 price, and it turns out to be coinsurance applied to a hospital charge.

So when we compare plans with someone, we do not start with the premium. We start with their doctors, their prescriptions and the one bad year they would want to be protected against. Then we look at how each plan prices those exact things: copay or coinsurance, before or after the deductible, and where the out-of-pocket limit sits. As independent brokers working across multiple carriers, we can lay these out side by side instead of showing you one company’s version.

The other thing we push on is timing. A plan that fits at 65 may not fit at 70 once your prescriptions or providers change. That is why we review plans with clients every year and stay available for claims questions and appeals, not just at enrollment.

— Zach

Get help comparing your real costs

If you are choosing between Medicare Advantage, a Medicare Supplement and a Part D drug plan, the copay and coinsurance details are where the plans really differ. We compare them for you across carriers, using your doctors and prescriptions, at no direct cost to you. Our brokerage is paid by carriers when you enroll. See our Medicare planning and plan comparison services or start with a Medicare Advantage consultation.

Simplyinsuranceforyou

If you are under 65 and shopping for individual or family coverage, our look at health insurance costs in Colorado is a good next step.

Common mistakes to avoid

Comparing copays across plans without comparing deductibles. A $15 copay means little if you pay full price until a $4,000 deductible is met.
Ignoring the network. Out-of-network care can carry higher coinsurance, balance bills, or no coverage at all, and balance bills do not count as cost sharing.
Forgetting facility fees. A visit that costs a $30 copay in an office can generate separate charges when done in a hospital outpatient department, as the Original Medicare example above shows. Our post on urgent care surprise bills and the $283 deductible shows how this plays out.
Assuming the out-of-pocket maximum covers everything. Premiums and non-covered services sit outside it.
Choosing on the lowest premium. HealthCare.gov’s guidance is to look at the total you could pay in a year.

FAQ

What is the difference between a copay and coinsurance?

A copay is a fixed dollar amount for a covered service, like $20 for a visit. Coinsurance is a percentage of the allowed amount, like 20%. A copay stays the same as the bill grows, while coinsurance grows with it.

Do I pay a deductible, copay and coinsurance on the same plan?

Often, yes. Many plans use all three for different services. You may pay the deductible first, then copays for routine care and coinsurance for larger services, until you reach the out-of-pocket maximum. Your summary of benefits lists which applies to what.

Is a copay or coinsurance better?

Neither is better in every case. Copays give predictable costs and often suit frequent, routine care. Coinsurance can cost less on inexpensive services and more on expensive ones, so a low out-of-pocket maximum matters more with coinsurance-heavy plans.

Does Original Medicare use copays or coinsurance?

Both. Part B usually charges 20% coinsurance after the $283 deductible in 2026, and hospital outpatient services can add a copayment per service, according to Medicare.gov. Original Medicare has no yearly out-of-pocket limit unless you add supplemental coverage or choose Medicare Advantage.

Do copays count toward the out-of-pocket maximum?

On many plans they do, along with the deductible and coinsurance. Plans differ, though, and premiums, balance bills and non-covered services never count. Check your plan’s documents or ask your broker before you rely on it.