What Is Coinsurance? Coinsurance vs. Copay vs. Deductible

What Is Coinsurance?

Coinsurance is a form of cost-sharing in which you pay a percentage of an eligible or covered cost while the insurer pays the remaining percentage, according to the terms of your insurance policy.

In health insurance, coinsurance is commonly expressed as a percentage such as 10%, 20%, 30% or 40%. If your coinsurance is 20%, you generally pay 20% of the applicable covered amount and the insurance plan pays the remaining 80%, subject to the plan's rules.

The word “after” is important.

In many health plans, the deductible comes before ordinary coinsurance. That means you might initially pay the full allowed cost of certain covered services until you reach your deductible. After that point, the plan may begin splitting covered costs between you and the insurer according to the coinsurance percentage.

However, this is not a universal rule for every health plan or every medical service. Some plans cover certain services before the deductible, and some services may have fixed copayments instead of coinsurance. The actual plan documents control.

This is why reading the phrase “20% coinsurance” by itself is not enough to determine your total healthcare cost.

You also need to know the deductible, out-of-pocket maximum, network rules, allowed amount, covered services and any service-specific cost-sharing provisions.

How Does Coinsurance Work?

The easiest way to understand coinsurance is to follow a claim from beginning to end.

Imagine a health insurance plan with:

• A $2,000 annual deductible.
• 20% coinsurance after the deductible.
• An $8,000 annual out-of-pocket maximum.

Suppose you receive a covered medical service with an allowed amount of $5,000.

If you have not paid anything toward your deductible yet, you may first be responsible for the applicable $2,000 deductible.

That leaves $3,000 of the covered amount.

Your 20% coinsurance would then apply to that $3,000.

The insurer would generally be responsible for the remaining eligible amount, assuming the service is covered and all other plan conditions are satisfied.

In this simplified example, your cost is therefore:

Coinsurance Example: A $10,000 Medical Bill

Let's make the calculation more realistic.

Suppose your health plan has:

• $1,500 deductible.
• 20% coinsurance.
• $6,000 out-of-pocket maximum.

You receive covered hospital treatment with an allowed amount of $10,000.

First, you pay the $1,500 deductible.

The remaining $8,500 is subject to 20% coinsurance.

So your simplified cost would be $3,200, while the insurer would pay the remaining eligible amount, subject to the policy.

Notice something important: 20% coinsurance did not mean you paid 20% of the entire $10,000.

You first paid the deductible and then paid 20% of the remaining applicable amount.

This is one of the biggest reasons people misunderstand coinsurance.

Coinsurance Is Not the Same as Paying 20% of Every Bill

If an insurance plan says “20% coinsurance,” it is tempting to think:

That is not necessarily how the calculation works.

In many health insurance arrangements, coinsurance is based on the plan's allowed amount or other contractually defined eligible amount rather than simply the provider's sticker price.

For example, imagine a provider charges $2,000 for a covered service but the applicable allowed amount under the plan is $1,200.

If your coinsurance is 20%, the relevant calculation may be based on the $1,200 allowed amount rather than the $2,000 billed charge, assuming the service and provider arrangement qualify under the plan.

The precise treatment depends on network status, local law and the plan's terms.

This is why you should not calculate your healthcare budget solely from the provider's advertised price.

What Is a Deductible?

A deductible is generally the amount you must pay for covered services before the insurer begins paying according to the plan's normal cost-sharing structure.

Suppose your deductible is $2,000.

If a covered service subject to the deductible has an allowed cost of $500, you may have to pay that $500 yourself.

After several services, suppose you have paid $1,800 toward the deductible. You then receive another covered service with an applicable allowed amount of $500.

You may pay the remaining $200 needed to reach the deductible, after which the plan's coinsurance or copayment rules can apply to the remaining $300, assuming the service is subject to those rules.

There can be important exceptions. Some plans cover certain services before the deductible, and some services can have their own cost-sharing rules.

Never assume that every medical service is treated identically.

What Is a Copay?

A copay, or copayment, is generally a fixed dollar amount that you pay for a covered service.

For example, your plan might require:

• $25 for a primary-care visit.
• $50 for a specialist visit.
• $15 for certain prescription medicines.
• $100 for a particular emergency service.

Unlike coinsurance, the amount is generally fixed rather than calculated as a percentage of the service's allowed cost.

However, whether the copay applies before or after the deductible depends on the plan.

Some plans have services with copays that apply even before the deductible, while other plans may require the deductible to be met first.

This is another reason the words “copay” and “deductible” cannot be treated as interchangeable.

For a useful overview of how insurance policies, premiums, deductibles and claims fit together, see Provenzy's guide to how insurance works.

Coinsurance vs. Copay vs. Deductible

These three terms describe different ways that an insurance plan can divide financial responsibility between the insurer and the policyholder.

Coinsurance vs. Copay: Which One Costs More?

Neither is automatically more expensive.

It depends on the price of the service.

Suppose one plan charges a $40 copay for a medical service.

Another plan charges 20% coinsurance.

If the applicable cost is $100, the coinsurance would be $20, which is cheaper than the $40 copay.

But if the applicable cost is $1,000, 20% coinsurance would be $200, which is much more than the $40 copay.

This is why a plan with a low copay is not automatically cheaper overall. You need to consider the entire cost-sharing structure.

How the Deductible and Coinsurance Work Together

One of the most important concepts in health insurance is that the deductible and coinsurance can work sequentially.

Consider a plan with:

• $1,000 deductible.
• 20% coinsurance.
• $5,000 out-of-pocket maximum.

You have a covered service with an allowed amount of $4,000.

First, you pay $1,000 toward the deductible.

There is then $3,000 remaining.

Your 20% coinsurance is $600.

The insurer would generally cover the remaining $2,400 of the eligible amount, subject to the plan.

This is the basic structure behind many health insurance calculations.

What Is an Out-of-Pocket Maximum?

An out-of-pocket maximum is a limit on how much you pay during a defined coverage period for certain covered services, subject to the plan's rules.

In plans that have an applicable out-of-pocket maximum, once you reach that limit for qualifying expenses, the insurer may pay 100% of covered services for the remainder of the relevant period, subject to the policy and network rules.

This creates an important relationship:

For example, suppose your plan has:

• $2,000 deductible.
• 20% coinsurance.
• $6,000 out-of-pocket maximum.

If you experience a serious medical event and accumulate enough qualifying cost-sharing expenses to reach $6,000, you may no longer have to pay additional qualifying covered in-network costs for the rest of the plan period, depending on the plan's rules.

The premium is generally separate from this calculation.

Costs for services the plan does not cover can also be outside the protection of the out-of-pocket maximum.

Out-of-network care may also be treated differently depending on the plan.

Does the Out-of-Pocket Maximum Include the Deductible?

In many health plans, qualifying deductible payments count toward the out-of-pocket maximum.

Coinsurance and copayments for qualifying covered services can also count.

But not every expense necessarily counts.

Premiums are generally separate from the out-of-pocket maximum in the health insurance framework commonly used in the United States. Costs for services that are not covered, and certain out-of-network or above-allowed-amount expenses, may also fall outside the limit.

Other countries and insurance systems can structure maximums differently, so international readers should check their own policy.

Why Coinsurance Can Become Expensive During Major Medical Events

Coinsurance can appear inexpensive when the underlying medical service is inexpensive.

A 20% share of a $100 service is only $20.

But 20% of $50,000 is $10,000.

This is why people should not judge health insurance based only on the coinsurance percentage.

A plan with 10% coinsurance may appear dramatically better than a plan with 30% coinsurance, but the difference could be offset by a higher premium, higher deductible or different out-of-pocket maximum.

A proper comparison looks at the entire structure.

How Coinsurance Can Affect Different Types of Healthcare

Coinsurance does not necessarily apply identically to every medical service.

A plan could use one cost-sharing method for primary-care visits, another for specialist care, another for hospital treatment and another for prescription medicines.

Doctor Visits

A plan may charge a fixed copay for certain routine visits rather than coinsurance.

Specialist Care

Specialist services can have a different copay or coinsurance percentage depending on the plan.

Hospital Care

Hospital services can generate much larger eligible costs, meaning a percentage-based coinsurance obligation can become significant.

Prescription Drugs

Prescription coverage can use copays, coinsurance, deductibles or tiered structures. Some plans have separate prescription deductibles.

Diagnostic Testing

Imaging, laboratory tests and diagnostic procedures can have their own cost-sharing rules.

Therefore, when estimating healthcare expenses, do not assume that the headline coinsurance percentage applies to every service you use.

How Provider Networks Affect Coinsurance

Network status can have a major effect on your actual cost.

A health plan may have a group of doctors, hospitals, laboratories and other providers that have agreed to negotiated rates or other contractual arrangements with the insurer.

When you use an in-network provider under a plan that has network-based cost sharing, the amount used to calculate your responsibility can be different from what happens when you use an out-of-network provider.

Some plans may pay less for out-of-network care. Others may provide no routine out-of-network coverage except for specified circumstances.

The provider's billed amount can also be different from the plan's allowed amount.

What Is an Allowed Amount?

The allowed amount is an important concept because coinsurance is often calculated using an eligible or allowed amount rather than the provider's undiscounted charge.

Suppose a provider's standard charge for a procedure is $3,000.

Your plan may have an allowed amount of $1,800 for that covered service under the applicable arrangement.

If your coinsurance is 20%, the simplified coinsurance calculation would be:

The calculation can be different if the service is subject to a deductible, copay, special benefit rule or out-of-network provision.

Understanding allowed amounts can make insurance bills much easier to interpret.

Coinsurance and Preventive Care

Some health insurance plans treat certain preventive services differently from other healthcare.

For example, a plan may cover specified preventive services without charging a deductible, copayment or coinsurance when the applicable conditions are satisfied.

This is one reason you should not assume that every medical service begins with the deductible.

Coverage can depend on the service, provider, network status, plan design and applicable local regulations.

If you are considering a preventive screening or vaccination, check the plan's current coverage information before assuming you will owe coinsurance.

Family Deductibles and Coinsurance

Family health plans can introduce another layer of complexity.

A family plan may have both individual and family deductible structures. This means the amount one family member pays can interact with the family's overall deductible depending on the plan design.

Once applicable deductibles are met, coinsurance and copayments may continue until the relevant out-of-pocket maximum is reached.

Imagine a family plan with:

• $2,000 individual deductible.
• $4,000 family deductible.
• 20% coinsurance.
• $7,000 individual out-of-pocket maximum.
• $14,000 family out-of-pocket maximum.

The exact operation of these amounts depends on whether the plan uses embedded, aggregate or another deductible structure.

This is why families should examine their plan's specific deductible rules rather than simply multiplying the individual deductible by the number of family members.

Coinsurance and High-Deductible Health Plans

Some health plans combine relatively high deductibles with coinsurance.

This can create a cost structure in which you are responsible for a significant amount early in the year and then continue paying a percentage of covered costs after the deductible.

Such plans can sometimes have lower premiums than plans with richer cost-sharing structures, but the trade-off is that you may face greater expenses when you actually use healthcare.

The important question is not:

The better question is:

That approach gives you a much clearer picture of the financial risk.

How to Estimate Your Annual Healthcare Costs

A useful way to compare plans is to build three scenarios.

Scenario 1: Low Healthcare Use

You use few medical services and mainly pay premiums plus occasional cost-sharing.

Scenario 2: Moderate Healthcare Use

You have several doctor visits, prescriptions and diagnostic services during the year.

Scenario 3: High Healthcare Use

You experience hospitalization, surgery, ongoing treatment or another major healthcare event.

For each scenario, estimate:

• Annual premiums.
• Deductible exposure.
• Expected copays.
• Expected coinsurance.
• Prescription costs.
• Potential out-of-pocket maximum.
• Network-related expenses.

This gives you a more realistic financial comparison than looking at the coinsurance percentage alone.

A Detailed Plan Comparison Example

Imagine two hypothetical health plans.

At first glance, Plan A looks cheaper because the annual premium is $1,200 lower.

But Plan B provides a lower deductible, lower coinsurance and lower out-of-pocket maximum.

If you rarely use healthcare, Plan A might produce lower total spending.

If you have a major medical event, Plan B could potentially produce lower cost-sharing, although the higher premium must still be included in the calculation.

There is no universally cheaper plan without knowing how much healthcare you actually use.

Common Coinsurance Mistakes

Mistake 1: Thinking Coinsurance Is the Premium

The premium is what you pay to maintain insurance coverage. Coinsurance is what you may pay when receiving applicable covered services.

Mistake 2: Thinking Coinsurance Is the Deductible

A deductible is generally a dollar threshold. Coinsurance is generally a percentage.

Mistake 3: Assuming 20% Means 20% of the Provider's Bill

The applicable calculation may be based on an allowed or eligible amount, depending on the plan and provider arrangement.

Mistake 4: Ignoring the Out-of-Pocket Maximum

The out-of-pocket maximum can be one of the most important numbers in evaluating financial risk.

Mistake 5: Comparing Plans Only by Premium

A lower premium can come with a higher deductible or higher coinsurance.

Mistake 6: Assuming Every Service Has the Same Coinsurance

Plans can have different cost-sharing rules for different categories of care.

Mistake 7: Ignoring Network Rules

Network status can affect what the plan pays and what you owe.

Mistake 8: Assuming the Deductible Always Comes First for Every Service

Some services may have different rules or may be covered before the deductible.

Mistake 9: Forgetting That Non-Covered Services May Not Receive Cost-Sharing Protection

Coinsurance applies to applicable covered services. It does not magically make an excluded service covered.

Mistake 10: Assuming Every Country Uses the Same Definitions

Insurance terminology and regulation vary internationally. Always check the actual policy wording.

How to Reduce the Financial Impact of Coinsurance

You cannot always eliminate coinsurance, but you can make it easier to manage.

1. Understand Your Plan Before You Need It

Know your deductible, coinsurance percentage, copays and out-of-pocket maximum.

2. Use Appropriate In-Network Providers

Where your plan uses provider networks, staying within the network can help you access the plan's negotiated or preferred cost-sharing structure.

3. Check Coverage Before Expensive Treatment

For planned procedures, ask the insurer what portion is expected to be covered and what cost-sharing rules apply.

4. Keep Track of Your Deductible

Many insurers provide online dashboards showing how much of your deductible and out-of-pocket maximum you have already satisfied.

5. Track Your Out-of-Pocket Spending

Keep explanations of benefits, receipts and medical bills so you can identify errors.

6. Compare Total Annual Costs

When choosing a new plan, compare premiums plus realistic cost-sharing rather than premiums alone.

You can also review Provenzy's detailed guide to insurance deductibles and how they work.

What Is Coinsurance in Property Insurance?

There is an important complication: coinsurance does not always mean the same thing in every type of insurance.

In health insurance, coinsurance usually means the percentage of a covered healthcare cost that you pay.

In some property and commercial insurance policies, however, a coinsurance clause can refer to a requirement that you insure property to a specified percentage of its value in order to receive full claim payment for a partial loss.

This is a completely different concept.

Because this article is aimed primarily at people searching for the health-insurance meaning of coinsurance, the remainder of this section explains the property concept separately.

How a Property Insurance Coinsurance Clause Can Work

Imagine a commercial building has a replacement value of $1,000,000.

The policy contains an 80% coinsurance requirement.

To satisfy the requirement, the property may need to be insured for at least:

Suppose the owner insures the building for only $600,000.

A covered partial loss causes $200,000 of damage.

A simplified coinsurance calculation might look like:

This is only a simplified illustration. Actual property claims can involve deductibles, policy wording, valuation provisions, limits and other conditions.

The important point is that property coinsurance and health coinsurance are not the same thing.

Why the Two Meanings of Coinsurance Cause Confusion

Someone might hear an insurance professional say “20% coinsurance” and assume the term always refers to the percentage of a claim they must pay.

That is usually the health-insurance interpretation.

But a property insurance professional may use “coinsurance” to describe a completely different policy mechanism related to the amount of insurance carried relative to the property's value.

Therefore, when discussing insurance, always identify the type of insurance involved.

Coinsurance and International Insurance Markets

Insurance terminology can vary across countries.

In some markets, health plans may use terms such as co-payment, excess, deductible, patient contribution or cost-sharing instead of exactly the terminology commonly used in the United States.

Even when the word “coinsurance” appears in a policy, the contractual definition is more important than the dictionary definition.

The same percentage can also have different practical effects depending on whether the insurer calculates it from the provider's charge, an agreed amount, a schedule of benefits, a negotiated rate or another defined basis.

For an international audience, the safest rule is:

This is especially important when receiving medical treatment abroad, using international health insurance or comparing policies issued in different countries.

Coinsurance vs. Copay vs. Deductible: A Real-Life Scenario

Let's put all three concepts together.

Imagine Sarah has a health plan with:

• $2,000 deductible.
• $30 primary-care copay.
• 20% coinsurance after the deductible for hospital care.
• $7,000 out-of-pocket maximum.

January: Doctor Visit

Sarah visits her primary-care doctor.

The applicable plan rule says she owes a $30 copay.

She pays $30.

March: Medical Test

Sarah receives a covered diagnostic test subject to the deductible. The applicable allowed cost is $500.

She pays the $500, bringing her deductible progress to $500.

June: Hospital Treatment

Sarah receives covered hospital care with an allowed amount of $6,000.

She has already paid $500 toward her $2,000 deductible.

She therefore has another $1,500 of deductible responsibility.

The remaining $4,500 is then subject to 20% coinsurance under the hypothetical plan.

Sarah's healthcare spending therefore contains different types of cost-sharing: a copay for one service, deductible spending for another, and deductible plus coinsurance for the hospital treatment.

This is exactly why learning the terminology matters.

How to Read a Health Insurance Cost-Sharing Table

When you compare health plans, look for a table showing the cost of different services.

You might see something like:

This is only an illustrative table. Actual plans can look very different.

The key is to look beyond the headline percentage and understand what happens before and after the deductible.

What Questions Should You Ask Before Choosing a Plan?

Before choosing an insurance plan, ask:

1. What is the annual premium?
2. What is the deductible?
3. Is there an individual and family deductible?
4. What is the coinsurance percentage?
5. Which services are subject to coinsurance?
6. Which services use copays instead?
7. Do copays apply before the deductible?
8. What is the out-of-pocket maximum?
9. What expenses count toward the out-of-pocket maximum?
10. Are there separate deductibles for prescriptions?
11. How are out-of-network services treated?
12. What is the plan's allowed amount or negotiated rate structure?
13. Are there services with special cost-sharing rules?
14. What happens in an emergency?
15. Which hospitals and doctors are in-network?

The answers can dramatically change the financial value of a plan.

How to Avoid Surprise Costs Related to Coinsurance

You cannot eliminate every unexpected healthcare expense, but you can reduce the risk of being surprised.

What If Your Coinsurance Calculation Looks Wrong?

Insurance billing errors can happen.

If you believe your coinsurance amount is incorrect, do not immediately assume that you must pay it.

First compare:

• The medical provider's bill.
• The insurer's explanation of benefits or claim statement.
• Your policy or plan summary.
• Your deductible progress.
• Your out-of-pocket maximum progress.
• The provider's network status.
• The allowed amount.
• The applicable coinsurance percentage.

If something does not match, contact the insurer and ask for a detailed explanation.

If necessary, ask the provider's billing department to review the claim as well.

Keep records of phone calls, letters, claim numbers and documents.

If an insurer denies a claim or refuses to correct an apparent error, the policy or applicable regulations may provide an appeal or complaint process.

How Coinsurance Affects Your Insurance Budget

Coinsurance is not merely an insurance vocabulary term. It is a budgeting issue.

If you choose a plan with a high coinsurance percentage, you should understand how much money you could realistically need if you experience a major medical event.

Consider two people.

Person A

Person A has a relatively high deductible and 30% coinsurance but maintains substantial emergency savings.

Person B

Person B has limited savings and would struggle to pay a large medical bill.

Even if Person A and Person B have similar incomes, the same insurance plan could create very different levels of financial risk.

This is why insurance should be evaluated alongside your emergency fund and overall financial plan.

Should You Choose a Lower Coinsurance Percentage?

A lower coinsurance percentage can reduce your share of applicable covered costs, but you generally should not choose a plan based on that number alone.

A plan with 10% coinsurance might have:

• A much higher premium.
• A higher deductible.
• A different out-of-pocket maximum.
• Different copays.
• A narrower provider network.

A plan with 30% coinsurance might have a lower premium and a different deductible structure.

The best plan depends on the total package.

Coinsurance and Your Financial Planning

A good insurance strategy should fit into your broader financial plan.

If your policy exposes you to a $7,000 or $10,000 potential out-of-pocket maximum, your emergency savings should ideally be considered alongside that exposure.

This does not mean everyone should keep the entire maximum in cash at all times. Financial circumstances differ.

But it does mean that an insurance plan should not be evaluated in isolation from your ability to absorb the costs it can leave with you.

A lower premium can be attractive, but if a major illness would force you into high-interest debt because you cannot afford the deductible and coinsurance, the apparent monthly savings may not represent the best overall financial choice.

Conversely, paying substantially more for a richer plan may not be worthwhile for someone with very low healthcare use and strong financial reserves.

Insurance is fundamentally about transferring risk. Coinsurance determines how much of certain covered costs remain with you after the plan begins sharing the expense.

Coinsurance and Health Insurance Premiums

Premiums and coinsurance are connected to the overall design of a plan, but they are not the same payment.

Your premium is generally the amount you pay to maintain coverage.

Coinsurance is generally what you pay when you use applicable covered services.

A plan with a higher premium may offer lower deductibles, copays or coinsurance, although this is not guaranteed.

A plan with a lower premium may shift more of the financial risk to you when you receive healthcare.

Therefore, the question is not simply:

It is:

A Simple Coinsurance Formula

For a simplified health-insurance example, once the applicable deductible has been satisfied:

For example, if the applicable allowed amount is $2,000 and your coinsurance is 20%:

If you had not yet met a deductible that applies to this service, the calculation could be different.

Coinsurance vs. Deductible: The Easiest Way to Remember

If you keep confusing these two terms, use this simple mental model:

That simple framework will help you understand most basic health insurance cost-sharing conversations.

How to Explain Coinsurance to Someone in One Sentence

If someone asks you what coinsurance means, the simplest accurate answer is:

Then add:

That distinction captures the central difference among the three terms.

Frequently Asked Questions About Coinsurance