Health Insurance Glossary: Common Terms Explained in Plain English

Health insurance comes with a vocabulary of its own. You may be comparing plans and suddenly find yourself looking at premiums, deductibles, coinsurance, provider networks, formulas, out-of-pocket maximums, and prior authorization requirements—all before you have even decided which plan to choose.

The good news is that most of these terms are easier to understand once someone explains what they actually mean and how they affect you. At AZ Health Insurance Agents, led by Clayton Eidson, we believe understanding your coverage is just as important as finding coverage in the first place. Knowing the language can help you compare plans more confidently, understand medical bills and claims, and ask better questions before you enroll.

The Beginner’s Guide to Health Insurance from AZ Health Insurance Agents introduces many of the terms below as part of understanding health insurance costs, provider networks, enrollment, claims, and Explanation of Benefits statements. This expanded glossary adds other terms people commonly encounter when researching individual, family, Marketplace, and private health insurance.

ACA — Affordable Care Act

The Affordable Care Act (ACA) is the federal healthcare law enacted in 2010. Among other things, it established consumer protections and created the framework for the Health Insurance Marketplace, where eligible individuals and families can compare qualified health plans and may qualify for financial assistance based on applicable rules.

You may also hear people use terms such as ACA plan, Marketplace plan, or sometimes Obamacare plan when referring to individual health coverage sold through the Marketplace.

AHCCCS

AHCCCS, pronounced “access,” stands for the Arizona Health Care Cost Containment System. It is Arizona’s Medicaid agency and provides healthcare programs for Arizona residents who meet applicable eligibility requirements, including income and other criteria.

AHCCCS is different from purchasing a private health insurance policy or Marketplace plan. If you are unsure which type of coverage you may qualify for, it helps to first understand the differences rather than assuming every health insurance option works the same way.

Allowed Amount

The allowed amount is the amount a health plan recognizes for a covered healthcare service. CMS describes it as the maximum payment a plan will pay for a covered service and notes that it may also be called an eligible expense, payment allowance, or negotiated rate.

For example, a doctor may bill $300 for a service while your plan’s allowed amount is $180. Depending on your deductible, copay, coinsurance, network status, and other plan rules, your share of the cost may be based on that allowed amount rather than simply the provider’s original charge.

Balance Billing

Balance billing can occur when a healthcare provider bills you for the difference between what the provider charged and what the health plan recognizes or pays. CMS notes that this occurs most commonly with out-of-network providers, while participating network providers generally cannot balance bill patients for covered services under their network contract.

There are also federal protections against certain surprise medical bills, including many emergency situations and certain out-of-network services received at in-network facilities. Because the rules depend on the circumstances, an unexpected bill deserves a closer look rather than an assumption that the entire balance must automatically be paid.

Claim

A claim is a request submitted to your health insurance company for payment or processing of healthcare services you received. In many situations, the doctor, hospital, laboratory, pharmacy, or another provider submits the claim on your behalf.

Your insurance company reviews the claim according to the terms of your health plan. After it is processed, you may receive an Explanation of Benefits (EOB) showing how the claim was handled, how much the plan paid, and what amount may be your responsibility. CMS describes the EOB as a record showing the cost of care and how the health plan processed the claim.

Coinsurance

Coinsurance is the percentage of a covered healthcare cost that you may be responsible for after satisfying the applicable deductible. For example, if a plan has 20% coinsurance for a service and the applicable allowed amount is $200, your share may be $40 while the plan pays its portion, assuming the deductible and other plan conditions have been met. CMS uses the same percentage-based framework when explaining coinsurance.

Coinsurance is different from a copay because a copay is generally a fixed dollar amount, while coinsurance is generally a percentage of an applicable cost.

Copay or Copayment

A copay, short for copayment, is a fixed amount you may pay for a covered healthcare service. A plan might have one copay for a primary care visit, another for a specialist, and different amounts for prescription drugs or other services.

Not every service uses a copay, and the relationship between copays and your deductible varies by plan. That is why it is important to look at the full cost structure rather than assuming a plan with a low office-visit copay will necessarily have the lowest overall cost.

Covered Services

Covered services are healthcare services, treatments, or benefits that your health insurance plan agrees to cover according to the terms of the policy. Clayton’s guide uses examples such as doctor visits, preventive care, emergency services, hospital stays, prescription medications, laboratory testing, mental health care, and maternity care, while also emphasizing that coverage varies by plan.

A service being generally associated with health insurance does not mean every plan covers it in exactly the same way. Network restrictions, medical necessity rules, prior authorization, exclusions, deductibles, and other plan provisions can still affect how a particular service is covered.

Deductible

A deductible is the amount you may have to pay toward certain covered healthcare services before your insurance plan begins sharing eligible costs. Deductibles vary between plans, and some healthcare services may be covered before the deductible is fully met.

A lower deductible can sound attractive, but it should not be evaluated by itself. Plans can have different premiums, networks, copays, coinsurance, prescription benefits, and out-of-pocket limits. Looking at those pieces together gives you a better picture of what the plan may actually cost.

Dependent

A dependent is an eligible person who can be covered under another person’s health insurance plan according to the plan’s eligibility rules. Depending on the coverage, this may include a spouse, children, or other qualifying family members.

The exact eligibility requirements depend on the plan and type of coverage. AZ Health Insurance Agents already has a dedicated resource explaining dependent coverage and some of the situations people may encounter when adding family members.

EOB — Explanation of Benefits

An Explanation of Benefits, or EOB, is a statement from your insurance company explaining how a healthcare claim was processed. It commonly shows the provider, date of service, amount billed, allowed amount, amount the insurer paid, and what amount may be your responsibility. CMS specifically notes that an EOB is not a medical bill.

EOB’s are worth reviewing because they can help you understand your deductible and cost-sharing, compare the claim with a provider bill, and identify a service or charge you do not recognize.

EPO — Exclusive Provider Organization

An EPO, or Exclusive Provider Organization, is a type of health plan that generally focuses coverage within a specific provider network. Out-of-network care is generally not covered except in situations such as emergency care, although the exact terms depend on the plan. EPO is one of the plan types included in the federal HealthCare.gov glossary.

An EPO may appeal to someone who wants network-based coverage without some of the referral structures associated with other plan types, but network access should be checked carefully before enrolling.

Formulary

A formulary is the list of prescription drugs covered by a health insurance plan. Prescription medications may be organized into different tiers, and your cost can vary depending on the medication, tier, pharmacy, and other plan rules. HealthCare.gov includes formulary as a standard health insurance term.

If you regularly take medication, checking the formulary before choosing coverage can be just as important as checking your doctors. Two plans with similar premiums and deductibles can still handle the same prescription very differently.

HMO — Health Maintenance Organization

An HMO, or Health Maintenance Organization, is a type of health plan that generally focuses on care within its provider network. Depending on the plan, you may choose a primary care physician and may need referrals before seeing certain specialists. HMO is one of the standard plan types recognized by HealthCare.gov.

The tradeoff is often between network structure and flexibility. Someone whose preferred doctors are already in the network may view an HMO very differently from someone who wants broader access to providers outside that network.

HSA — Health Savings Account

A Health Savings Account (HSA) is a tax-advantaged account that eligible individuals can use to pay certain qualified medical expenses. HSA eligibility is connected to enrollment in a qualifying High Deductible Health Plan and other federal requirements, so not every health insurance plan can be paired with an HSA. HealthCare.gov includes both HSA and HDHP as standard coverage terms.

An HSA and your health insurance policy are not the same thing. The health plan provides insurance coverage, while the HSA is an account that can be used for eligible healthcare expenses under applicable tax rules.

In-Network

In-network refers to doctors, hospitals, pharmacies, laboratories, and other providers that have a contractual relationship with your health insurance plan. Using in-network care generally means receiving the plan’s negotiated rates and more favorable cost-sharing than voluntarily using an out-of-network provider.

The key is to check your specific plan, not simply the insurance carrier’s name. A provider may participate with one network offered by an insurance company but not another.

Marketplace — Health Insurance Marketplace

The Health Insurance Marketplace is a platform where eligible consumers can compare and enroll in individual and family health coverage. Depending on eligibility, some consumers may qualify for premium tax credits or other financial assistance when purchasing Marketplace coverage. HealthCare.gov includes Marketplace, qualified health plans, premium tax credits, and cost-related assistance in its official health insurance terminology.

Arizona consumers evaluating Marketplace coverage still need to compare more than price. Provider networks, prescriptions, deductibles, out-of-pocket limits, and plan types remain important when deciding which available option fits their situation.

Network

A provider network is the group of doctors, hospitals, pharmacies, laboratories, facilities, and other healthcare providers that have contracted with a particular health plan. HealthCare.gov includes both “network” and “network plan” in its standard glossary.

Networks are one of the areas people sometimes overlook when they focus primarily on the monthly premium. If keeping a particular doctor, specialist, or hospital matters to you, check the exact network before enrolling rather than assuming the provider participates because they recognize the insurance company’s name.

Open Enrollment

Open Enrollment is the annual period when eligible consumers can enroll in or change qualifying individual health coverage for the upcoming coverage year. Outside of Open Enrollment, you generally need to qualify for a Special Enrollment Period or another available coverage path to make certain enrollment changes. HealthCare.gov maintains both Open Enrollment Period and Special Enrollment Period as separate terms in its glossary.

Enrollment rules can vary depending on the type of coverage, so do not assume that the Marketplace, employer coverage, Medicare, and other forms of insurance all follow the same calendar.

Out-of-Network

Out-of-network refers to a provider or facility that does not participate in your particular health plan’s network. Depending on the plan, voluntarily using an out-of-network provider can result in higher cost-sharing, limited benefits, or no coverage for certain non-emergency services.

PPOs may provide some out-of-network benefits, while other plan structures can be much more restrictive. Federal surprise-billing rules also provide protections in certain emergency and facility-based situations, but those protections do not mean every voluntary out-of-network service is automatically covered as though it were in-network.

Out-of-Pocket Maximum

The out-of-pocket maximum, sometimes called the out-of-pocket limit, is the most you may have to pay during a plan year for covered services that count toward the plan’s applicable limit. After you reach the limit, the plan generally pays 100% of covered in-network benefits for the remainder of the plan year, subject to the plan rules.

This number does not necessarily include everything you spend on healthcare. Premiums, services that are not covered, and certain out-of-network costs generally do not count toward the Marketplace plan’s in-network out-of-pocket limit. This is why comparing only deductibles can give an incomplete picture of financial exposure.

Policyholder

The policyholder is the person or entity that owns the insurance policy and is responsible for the contract. The policyholder may also have eligible dependents covered under the same policy, depending on the coverage and eligibility rules.

AZ Health Insurance Agents already has a dedicated article that goes deeper into policyholder responsibilities and how policyholders relate to dependents, making it a natural supporting resource from the glossary.

PPO — Preferred Provider Organization

A PPO, or Preferred Provider Organization, is a plan structure that generally provides more flexibility when choosing healthcare providers. Depending on the plan, members may be able to receive covered care outside the preferred network, but those services can come with higher costs. PPO is included among HealthCare.gov’s standard plan types.

That flexibility does not automatically make a PPO the right choice for everyone. Premiums, deductibles, prescriptions, provider access, and other costs should still be compared alongside the network structure.

Premium

A premium is the amount you pay to maintain your health insurance coverage, usually on a monthly basis. Paying the premium keeps coverage active, but it does not mean all healthcare is then free. Deductibles, copays, coinsurance, and other cost-sharing may still apply when you use covered services.

This is one of the most important concepts when comparing plans because the lowest monthly premium does not always result in the lowest overall healthcare spending. The Beginner’s Guide to Health Insurance specifically encourages consumers to consider premiums alongside deductibles, networks, prescription coverage, and other costs when comparing coverage.

Premium Tax Credit

A premium tax credit is financial assistance that can lower the cost of eligible Marketplace health insurance premiums for people who meet applicable requirements. It is tied to Marketplace coverage and eligibility rules rather than being a discount automatically available with every type of health insurance. HealthCare.gov lists the premium tax credit as a specific Marketplace term.

Eligibility and the amount of assistance can depend on factors such as household information and applicable income rules. Because these rules can change, consumers should use current Marketplace information when determining eligibility rather than relying on an older estimate.

Preventive Care

Preventive care generally refers to healthcare intended to help prevent illness or identify certain health concerns early, such as eligible screenings, immunizations, and preventive checkups. Clayton’s guide uses routine checkups, health screenings, immunizations, and wellness visits as examples while noting that actual coverage depends on the plan.

When discussing cost, it is important not to assume that every visit someone considers “preventive” will automatically be covered without cost-sharing. How a service is classified and whether applicable requirements are met can affect coverage.

Prior Authorization

Prior authorization, sometimes called preauthorization, is approval that a health plan may require before certain healthcare services, procedures, or medications are provided. HealthCare.gov includes prior authorization as a standard insurance term, while CMS advises consumers to check whether authorization is needed before receiving applicable care.

Prior authorization is not the same as a guarantee that every cost will be covered. Network status, eligibility, deductibles, copays, coinsurance, and other plan provisions can still affect what the patient ultimately owes.

Qualifying Life Event — QLE

A Qualifying Life Event (QLE) is a life change that may allow you to enroll in or change eligible health coverage outside the normal Open Enrollment period. Common examples can include marriage, birth or adoption, loss of qualifying coverage, and certain moves, depending on the applicable rules. HealthCare.gov maintains qualifying life event and Special Enrollment Period as related but separate terms.

Experiencing a life event does not mean you should wait indefinitely to review your options. Special Enrollment Periods have timing and eligibility rules, so it is important to check what applies to your particular situation.

Referral

A referral is a direction or authorization from one healthcare provider—often a primary care physician—to see another provider or specialist. Some health plan structures require referrals for certain specialist services, while others provide more flexibility. HealthCare.gov includes referral as a standard health insurance term.

If you have a condition that requires regular specialist care, referral requirements are worth checking before enrollment. A plan may have the doctors you want in-network but still require a particular process before specialist care is covered according to plan rules.

Special Enrollment Period — SEP

A Special Enrollment Period (SEP) is a period outside regular Open Enrollment when an eligible person may be allowed to enroll in or change health coverage because of a qualifying circumstance. A qualifying life event may create an SEP, but the eligibility requirements and timing depend on the situation and coverage type.

This distinction is useful: the QLE is the qualifying event, while the SEP is the enrollment opportunity that may result from it.

Summary of Benefits and Coverage — SBC

A Summary of Benefits and Coverage (SBC) is a standardized summary designed to help consumers understand and compare important features of health plans. HealthCare.gov includes the SBC as a standard health insurance term.

When comparing plans, the SBC can help you review features such as deductibles, cost-sharing, coverage examples, and other benefit information in a more consistent format. It should still be considered alongside provider directories, formularies, and complete plan documents when those details matter to your decision.

Frequently Asked Questions About Health Insurance Terms

What Are the Most Important Health Insurance Terms to Know?

For most people starting to compare coverage, the most useful terms are premium, deductible, copay, coinsurance, out-of-pocket maximum, provider network, covered services, and formulary. Understanding those terms gives you a much better picture of both what a plan costs and how you may use it.

What Is the Difference Between a Premium and a Deductible?

Your premium is the amount you pay to maintain the insurance policy, usually each month. Your deductible is an amount you may need to pay toward certain covered healthcare services before the health plan begins sharing eligible costs. Paying the monthly premium does not satisfy your deductible.

What Is the Difference Between a Copay and Coinsurance?

A copay is generally a fixed dollar amount, while coinsurance is generally a percentage of an applicable covered healthcare cost. A plan can use both depending on the services and benefit design.

What Is the Difference Between In-Network and Out-of-Network?

An in-network provider participates in your specific health plan’s contracted network, while an out-of-network provider does not. Out-of-network care may result in higher costs, limited benefits, or no routine coverage depending on the plan.

Is an Explanation of Benefits a Bill?

No. An EOB explains how your insurance company processed a claim; it is not a request for payment. Your healthcare provider may separately send a medical bill. CMS specifically distinguishes an EOB from a bill.

What Does “Subject to the Deductible” Mean?

When a covered service is subject to the deductible, you may be responsible for the applicable allowed cost until you have satisfied the relevant deductible, after which the plan’s other cost-sharing rules may apply. The exact treatment depends on your plan.

What's the Difference Between Open Enrollment and a Special Enrollment Period?

Open Enrollment is the regular annual opportunity to enroll in or change eligible coverage. A Special Enrollment Period is an additional enrollment opportunity available to people who meet qualifying circumstances outside that annual period

How These Health Insurance Terms Work Together

It helps to think of these terms as parts of the same system rather than separate definitions. Imagine that you enroll in a plan and pay your monthly premium to keep your coverage active. When you visit an in-network doctor, the provider submits a claim to your health plan. The plan determines the applicable allowed amount, then applies the rules for your deductible, copay, or coinsurance.

After the claim is processed, you may receive an EOB showing what the provider billed, what the plan recognized, what the insurance company paid, and what amount may be your responsibility. As you continue receiving covered in-network care during the year, eligible cost-sharing can move you closer to your out-of-pocket maximum.

That is why one health insurance term rarely tells you whether a plan is a good fit. Premiums, deductibles, networks, cost-sharing, prescriptions, enrollment rules, and benefits all connect to one another.

Which Health Insurance Terms Matter Most When Comparing Plans?

You do not need to memorize an entire insurance dictionary before choosing coverage. Start with the terms that have the biggest effect on how you access care and what you may pay: premium, deductible, out-of-pocket maximum, copay, coinsurance, provider network, prescription formulary, and covered services.

Then look at your own situation. If keeping a doctor matters, pay special attention to the network. If you use regular prescriptions, check the formulary. If you expect frequent medical care, the deductible and cost-sharing may matter more than they would for someone who rarely uses healthcare. The point is to evaluate how the pieces work together rather than choosing a plan because one number looks attractive.

AZ Health Insurance Agents’ consultation guide explains this same practical approach by looking at doctors, prescriptions, expected healthcare use, premiums, deductibles, and network considerations when discussing coverage options.

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Still Confused by Health Insurance Terminology?

Knowing the definitions is useful, but the harder part is usually understanding how those terms apply to the actual plans in front of you. Two plans can use the same words—premium, deductible, network, and coinsurance—while offering very different combinations of costs and benefits.

AZ Health Insurance Agents, led by Clayton Eidson, helps Arizona individuals and families make sense of those differences in clear, straightforward language. Clayton and the team can help you compare plan options, provider networks, prescription coverage, deductibles, cost-sharing, and other details so you understand what you are considering before making a coverage decision. The company currently serves individuals, families, and businesses looking at multiple types of Arizona health coverage.

The goal is not to memorize health insurance terminology. It is to understand enough of it to ask the right questions and make a more informed decision about your coverage.

Ready to talk through your health insurance options? Contact AZ Health Insurance Agents today to speak with Clayton Eidson and the team.