Health Insurance A–Z

Health insurance has its own vocabulary, and the words on a plan summary, a medical bill or a Marketplace application shape what you end up paying. These plain-English definitions are based on official sources such as HealthCare.gov, CMS, the IRS, the U.S. Department of Labor and the FTC, and every dollar figure names its year and source. This is general information, not insurance, tax, legal or medical advice; for help with your own situation, contact your state insurance department, a Marketplace Navigator or a licensed professional.

Advance premium tax credit (APTC): The premium tax credit taken during the year to lower your monthly premium, based on the income you estimate on your Marketplace application. You can use all, some or none of it in advance; if you use more than your final income qualifies you for, you pay back the excess when you file your federal tax return.; Related:Premium tax credit Reconciliation (premium tax credit)Form 1095-A
Agent and broker: Licensed insurance professionals who can help you enroll in a plan; agents may work for one insurance company, while brokers may represent several. HealthCare.gov says they often earn commissions from insurers, you pay nothing extra to use one, and they must enroll you through the Marketplace for you to get Marketplace savings.; Related:Navigator Health Insurance Marketplace Premium tax credit
Allowed amount: The maximum amount a plan will pay for a covered service, also called the eligible expense, payment allowance or negotiated rate. Coinsurance is usually figured from this amount, and if a provider charges more than it, you may be billed for the difference.; Related:Balance billing Coinsurance Network
Appeal: A request for your insurer, or the Marketplace, to review a decision that denies a benefit or payment. In an internal appeal you ask the plan itself to reconsider; HealthCare.gov says you must file within 180 days of being notified of the denial, and if the plan still says no, you can request an external review.; Related:External review Claim Explanation of Benefits (EOB)
Balance billing: When a provider bills you for the difference between its charge and your plan's allowed amount. HealthCare.gov says a preferred (in-network) provider may not balance bill you for covered services, and the No Surprises Act protects you from these surprise bills in situations such as emergency room visits.; Related:Allowed amount No Surprises Act Network
Catastrophic plan: A Marketplace plan available to people under 30, and to people 30 and older who qualify for a hardship or affordability exemption. HealthCare.gov says it covers the same 10 essential health benefits as other Marketplace plans, including preventive services at no cost, and at least three primary care visits a year before the deductible is met, with premiums that are generally lower and out-of-pocket costs that are generally higher than other plans.; Related:Metal levels High deductible health plan (HDHP)Deductible
Children's Health Insurance Program (CHIP): A program that provides low-cost coverage to children in families that earn too much to qualify for Medicaid but not enough to buy private insurance; some states also cover pregnant women. Each state's CHIP works closely with its Medicaid program, and you can apply any time of year.; Related:Medicaid Federal poverty level (FPL)Dependent coverage
Claim: A request for payment that you or your provider submits to your health insurer for care you believe is covered. If the plan denies a claim, HealthCare.gov says it must tell you in writing and explain why, and you can appeal.; Related:Explanation of Benefits (EOB)Appeal Allowed amount
COBRA: A federal law that may let you temporarily keep job-based group coverage after a job loss, reduced hours, divorce, death or another qualifying event. As of 2026, the U.S. Department of Labor says COBRA generally applies to employers with 20 or more employees and that you may have to pay the entire premium, up to 102% of the plan's cost.; Related:Special Enrollment Period (SEP)Qualifying life event (QLE)Premium
Coinsurance: Your share of the cost of a covered service, expressed as a percentage of the plan's allowed amount (for example, a hypothetical 20%). You typically pay coinsurance after meeting your deductible, until you reach your out-of-pocket maximum.; Related:Allowed amount Deductible Out-of-pocket maximum
Copayment (copay): A fixed dollar amount you pay for a covered service, such as an office visit or a prescription, often at the time you get care. Copays can differ by type of service within the same plan, so check your plan documents to see which services have one and whether it applies before or after the deductible.; Related:Coinsurance Deductible Cost sharing
Cost sharing: The part of the cost of covered care that you pay yourself, such as deductibles, copayments and coinsurance. HealthCare.gov explains that it doesn't include premiums, balance bills from out-of-network providers or the cost of services your plan doesn't cover.; Related:Copayment (copay)Coinsurance Cost-sharing reductions (CSRs)
Cost-sharing reductions (CSRs): Discounts, often called "extra savings," that lower deductibles, copayments, coinsurance and the out-of-pocket maximum for people who qualify through their Marketplace application. You get them only by enrolling in a Silver plan, while premium tax credits can be used with a plan at any metal level.; Related:Metal levels Premium tax credit Cost sharing
Deductible: The amount you pay for covered services before your plan starts to pay its share. HealthCare.gov notes that Marketplace plans pay the full cost of certain preventive services even before you meet the deductible, and family plans often have both an individual deductible for each person and a family deductible for everyone.; Related:Premium Coinsurance Preventive services
Dependent coverage: Coverage for a policyholder's family members, such as a spouse or children. HealthCare.gov says young adults can usually stay on a parent's plan that covers dependents until they turn 26, and on a Marketplace plan, through December 31 of the year they turn 26.; Related:Qualifying life event (QLE)Special Enrollment Period (SEP)Health Insurance Marketplace
Essential health benefits: Ten categories of services that health plans must cover under the Affordable Care Act, including doctors' services, inpatient and outpatient hospital care, prescription drugs, pregnancy and childbirth, and mental health services. Dental coverage for children is included while adult dental is optional, and specific services vary by state.; Related:Pre-existing condition Preventive services Summary of Benefits and Coverage (SBC)
Exclusive Provider Organization (EPO): A managed care plan that covers services only when you use doctors, specialists or hospitals in the plan's network, except in an emergency.; Related:Network Health Maintenance Organization (HMO)Preferred Provider Organization (PPO)
Explanation of Benefits (EOB): A statement your health plan sends after you get care, showing the services, what was charged, what the plan covered and what you may owe. CMS stresses that an EOB is not a bill, and the FTC lists an EOB for services you didn't receive as a warning sign of medical identity theft.; Related:Claim Medical identity theft Appeal
External review: A review of a plan's denial by an independent third party not related to the plan, usually after an internal appeal fails (or at the same time, in urgent situations). It's available for denials based on medical necessity, care considered experimental or investigational, rescission of coverage and similar decisions, and the plan must accept the outcome.; Related:Appeal Prior authorization Claim
Federal poverty level (FPL): An income measure updated each year by the U.S. Department of Health and Human Services and used to determine eligibility for Marketplace savings, Medicaid and CHIP. HealthCare.gov lists 2026 figures of $15,960 for one person and $33,000 for a family of four (2025: $15,650 and $32,150), with higher amounts in Alaska and Hawaii. It says 2026 figures are used for Medicaid and CHIP, while Marketplace savings use the previous year's figures, so 2026 Marketplace coverage uses the 2025 amounts and 2027 coverage uses the 2026 amounts.; Related:Premium tax credit Medicaid expansion Modified Adjusted Gross Income (MAGI)
Flexible Spending Account (FSA): An employer arrangement that lets you pay many out-of-pocket medical costs, such as copays, deductibles and prescriptions, with pre-tax money you choose to set aside. For 2026, IRS Revenue Procedure 2025-32 limits salary-reduction contributions to $3,400 and allows a carryover of up to $680 if the plan permits; HealthCare.gov notes an employer can offer either a carryover or a 2.5-month grace period, not both.; Related:Health Savings Account (HSA)Health Reimbursement Arrangement (HRA)Cost sharing
Form 1095-A: The Health Insurance Marketplace Statement, sent by the Marketplace (not the IRS) if anyone in your household had a Marketplace plan other than a Catastrophic plan. It lists your premiums, any premium tax credit you used and your second lowest cost Silver plan (SLCSP) premium, which you need for Form 8962; HealthCare.gov advises not filing your taxes until you have an accurate 1095-A.; Related:Reconciliation (premium tax credit)Advance premium tax credit (APTC)Premium tax credit
Formulary: A plan's list of covered prescription drugs, also called a drug list. Checking it before you enroll shows whether the medicines you take are covered.; Related:Prior authorization Cost sharing Summary of Benefits and Coverage (SBC)
Good faith estimate: An estimate of expected charges that providers usually must give people who don't have or aren't using health insurance, when they schedule care at least three business days ahead or ask for one. As of 2026, CMS says you may be able to dispute a bill that is at least $400 more than the estimate.; Related:No Surprises Act Balance billing Claim
Health Insurance Marketplace: The shopping and enrollment service for individual and family health coverage created by the Affordable Care Act, also called the exchange. In most states the federal government runs it at HealthCare.gov, while some states run their own; your application also shows whether you qualify for savings, Medicaid or CHIP.; Related:Open Enrollment Period Premium tax credit Metal levels
Health insurance scams: Schemes that pose as coverage help to collect money or personal information. HealthCare.gov says the Marketplace, its assisters and your state will never threaten you or ask for credit card information or payment to keep or qualify for coverage, and it urges caution with social media ads offering cash, gifts or other perks; look for official websites ending in .gov.; Related:Navigator Medical identity theft State insurance department
Health Maintenance Organization (HMO): A plan type that usually limits coverage to care from doctors who work for or contract with the HMO and generally won't cover out-of-network care except in an emergency. An HMO may require you to live or work in its service area, and many require a referral from your primary care doctor before you see anyone else.; Related:Referral Primary care provider Network
Health Reimbursement Arrangement (HRA): An employer-funded group health plan that reimburses employees tax-free for qualified medical expenses up to a fixed dollar amount each year; the employer funds and owns it, and unused amounts may roll over. One version, the individual coverage HRA, reimburses expenses such as premiums for individual insurance and can affect whether you qualify for premium tax credits.; Related:Flexible Spending Account (FSA)Health Savings Account (HSA)Premium tax credit
Health Savings Account (HSA): A tax-advantaged account you can contribute to only while covered by an HSA-eligible plan: money goes in pre-tax, earnings aren't taxed, and you can use it for deductibles, copayments, coinsurance and other qualified medical expenses, but generally not premiums. For 2026, IRS Revenue Procedure 2025-19 caps contributions at $4,400 for self-only coverage and $8,750 for family coverage; for 2027, IRS Revenue Procedure 2026-24 raises the caps to $4,500 and $9,000.; Related:High deductible health plan (HDHP)Flexible Spending Account (FSA)Health Reimbursement Arrangement (HRA)
High deductible health plan (HDHP): A plan with a higher deductible than a traditional plan, usually with a lower premium; one that meets IRS rules is often called "HSA-eligible." For 2026, IRS Revenue Procedure 2025-19 sets the minimum HDHP deductible at $1,700 for self-only and $3,400 for family coverage, with out-of-pocket expenses capped at $8,500 and $17,000; for 2027, IRS Revenue Procedure 2026-24 sets $1,750 and $3,500, with caps of $8,700 and $17,400. The IRS also says that starting January 1, 2026, bronze and catastrophic plans are treated as HSA-compatible.; Related:Health Savings Account (HSA)Deductible Catastrophic plan
Medicaid: A joint federal and state program that provides free or low-cost coverage to some people with low incomes, families and children, pregnant women, older adults and people with disabilities. Each state's Medicaid agency determines eligibility, benefits and program names vary by state, and you can apply any time of year.; Related:Medicaid expansion Children's Health Insurance Program (CHIP)Modified Adjusted Gross Income (MAGI)
Medicaid expansion: A state's choice to cover all adults with household incomes below a set level. As of October 2026, HealthCare.gov says that in expansion states you qualify on income alone if it's below 133% of the federal poverty level, which works out to 138% because of how it's calculated (a few states use a different limit). In states that haven't expanded, adults below the poverty level who don't meet other state rules may qualify for neither Medicaid nor Marketplace savings.; Related:Medicaid Federal poverty level (FPL)Premium tax credit
Medical identity theft: When someone uses your personal information, such as your name, Social Security number, or health insurance or Medicare number, to get medical care, prescriptions or devices, or to submit claims to your insurer. The FTC warns that if the thief's health information gets mixed with yours, it could affect the care and benefits you can get, and that an unfamiliar bill or EOB is a warning sign.; Related:Explanation of Benefits (EOB)Health insurance scams Claim
Metal levels: The Marketplace plan categories (Bronze, Silver, Gold and Platinum), based on how you and your plan split the costs of care, not on the quality of care. Each category can include different plan types, such as HMOs and PPOs.; Related:Catastrophic plan Cost-sharing reductions (CSRs)Health Maintenance Organization (HMO)
Modified Adjusted Gross Income (MAGI): The income figure used to determine eligibility for premium tax credits, other Marketplace savings, Medicaid and CHIP. It's your adjusted gross income plus any untaxed foreign income, non-taxable Social Security benefits and tax-exempt interest; it excludes Supplemental Security Income and doesn't appear as a line on your tax return.; Related:Federal poverty level (FPL)Premium tax credit Medicaid
Navigator: A trained individual or organization that gives free, unbiased help with finding coverage through the Marketplace, including filling out eligibility and enrollment forms. Navigators are one kind of Marketplace "assister," and HealthCare.gov says assisters will never ask for payment or credit card information for you to keep or qualify for coverage.; Related:Agent and broker Health Insurance Marketplace Health insurance scams
Network: The facilities, providers and suppliers your health insurer has contracted with to provide care. Providers inside it are "in-network"; using out-of-network providers usually costs more or may not be covered at all, depending on the plan type.; Related:Health Maintenance Organization (HMO)Preferred Provider Organization (PPO)Exclusive Provider Organization (EPO)
No Surprises Act: A federal law, in effect since January 1, 2022, that protects people with most types of health insurance from unexpected out-of-network bills for emergency room visits, certain non-emergency care at in-network hospitals and surgical centers, and air ambulance services. It also generally requires providers to give people who don't use insurance a good faith estimate of costs.; Related:Balance billing Good faith estimate Network
Open Enrollment Period: The yearly window to enroll in or change a Marketplace plan. For 2027 coverage, HealthCare.gov and CMS (as of October 2026) list November 1, 2026 through January 15, 2027 at HealthCare.gov, with December 15, 2026 the last day to enroll for coverage starting January 1, 2027; if you use a state-run Marketplace, check its dates, and note that job-based plans set their own enrollment periods.; Related:Special Enrollment Period (SEP)Health Insurance Marketplace Qualifying life event (QLE)
Out-of-pocket maximum: The most you have to pay for covered, in-network services in a plan year; once you reach it, the plan pays 100% of covered benefits. It doesn't count premiums, out-of-network care, services the plan doesn't cover or charges above the allowed amount. For Marketplace plans, HealthCare.gov lists a limit of $10,600 for an individual and $21,200 for a family in 2026, and $12,000 and $24,000 in 2027.; Related:Deductible Cost sharing Allowed amount
Pre-existing condition: A health problem, such as asthma, diabetes or cancer, that you had before new coverage starts. HealthCare.gov says Marketplace plans can't reject you, charge you more or refuse to pay for essential health benefits because of one, and Medicaid and CHIP can't refuse you or charge more either; grandfathered individual plans are an exception.; Related:Essential health benefits Health Insurance Marketplace Medicaid
Preferred Provider Organization (PPO): A plan type that contracts with doctors, hospitals and other providers to form a network of participating providers. You pay less when you use the network, but you can also see out-of-network providers for an additional cost.; Related:Network Health Maintenance Organization (HMO)Exclusive Provider Organization (EPO)
Premium: The amount you pay to keep your health insurance active, usually every month, whether or not you use any care. It's separate from what you pay when you get care, such as deductibles, copayments and coinsurance, so the plan with the lowest premium isn't automatically the cheapest overall.; Related:Deductible Premium tax credit Out-of-pocket maximum
Premium tax credit: A federal tax credit that lowers the monthly premium on a plan bought through the Marketplace, which is the only place to get it. It's based on your household information and estimated income; as of October 2026, HealthCare.gov describes eligibility for household incomes between 100% and 400% of the federal poverty level, subject to other rules.; Related:Advance premium tax credit (APTC)Federal poverty level (FPL)Reconciliation (premium tax credit)
Preventive services: Routine care, such as screenings, check-ups, immunizations and counseling, meant to prevent illness. HealthCare.gov says most plans, including Marketplace plans, must cover a set of preventive services at no cost when you use an in-network provider, even before you meet your deductible, though $0 isn't guaranteed in every case.; Related:Deductible Essential health benefits Network
Primary care provider: A physician (MD or DO), nurse practitioner, clinical nurse specialist or physician assistant, as allowed under state law, who provides, coordinates or helps you access a range of health care services. Some plans, especially HMOs, route specialist care through this provider.; Related:Referral Health Maintenance Organization (HMO)Preventive services
Prior authorization: Approval from your health plan that may be required before you get a service or fill a prescription in order for it to be covered; also called preauthorization, prior approval or precertification. HealthCare.gov notes it isn't a promise that the plan will pay, and it isn't required for emergencies.; Related:Formulary Referral Appeal
Qualifying life event (QLE): A change in your situation that can make you eligible for a Special Enrollment Period. HealthCare.gov groups them into four types: losing health coverage, changes in household (like marriage, divorce or a birth), changes in residence, and other events, such as income changes that affect what you qualify for or becoming a U.S. citizen.; Related:Special Enrollment Period (SEP)Dependent coverage COBRA
Reconciliation (premium tax credit): The tax-time step of comparing the premium tax credit you used in advance with the amount you qualify for based on your final income, using IRS Form 8962. If you used too much, you pay the difference with your federal taxes; if you used too little, you get the difference as a credit.; Related:Advance premium tax credit (APTC)Form 1095-A Modified Adjusted Gross Income (MAGI)
Referral: A written order from your primary care doctor for you to see a specialist or get certain medical services. In many HMOs you need one before getting care from anyone other than your primary care doctor, and the plan may not pay if you skip it.; Related:Health Maintenance Organization (HMO)Primary care provider Prior authorization
Special Enrollment Period (SEP): A time outside Open Enrollment when you can sign up for coverage because of a qualifying life event, such as losing coverage, moving, getting married, having a baby or adopting. HealthCare.gov says you usually have 60 days before or after the event to enroll in a Marketplace plan, and job-based plans must offer at least 30 days.; Related:Qualifying life event (QLE)Open Enrollment Period COBRA
State Health Insurance Assistance Program (SHIP): A state program that receives federal funding to provide free, local health coverage counseling to people with Medicare. For Marketplace questions, a Navigator is the comparable free resource.; Related:Navigator State insurance department Medicaid
State insurance department: The state agency that regulates insurance and can provide information about health coverage in your state. It's a useful starting point when you have questions about an insurer, an agent or a plan sold where you live.; Related:Agent and broker Appeal Health insurance scams
Summary of Benefits and Coverage (SBC): A standardized, easy-to-read summary of a plan's costs and coverage that lets you compare plans apples to apples. You receive one when you shop for coverage on your own or through a job, when you renew or change coverage, or when you ask the insurer for it.; Related:Explanation of Benefits (EOB)Essential health benefits Deductible