Health Insurance Glossary: A-Z Terms Explained

Use the letter index to jump to a section, or scroll through the full list. Each definition is written in plain English first, with the formal meaning built in.

Actuarial Value: The percentage of total average costs for covered benefits a plan is designed to pay. Metal tiers are built around actuarial value: bronze plans target roughly 60%, platinum roughly 90%.
Adverse Selection: The tendency for people who expect to use more care to be more likely to enroll in insurance than healthy people, which can drive up costs for a plan or risk pool if not balanced by broad enrollment.
Affordable Care Act (ACA): The 2010 federal law that created the Health Insurance Marketplace, premium tax credits, guaranteed issue for pre-existing conditions, and the essential health benefits requirement.
Allowed Amount: The maximum amount a plan will pay for a covered service. In-network providers agree to accept this amount; out-of-network providers may bill you for the difference.
Ambulatory Care: Medical care provided on an outpatient basis, without an overnight hospital stay, such as an office visit, outpatient procedure, or same-day surgery center visit.
Annual Enrollment Period: See Open Enrollment Period.
Appeal: A formal request asking your insurer to reconsider a denied claim or service. Plans are required to have an appeals process, and many denials get reversed once appealed.
Assignment of Benefits: An arrangement where you authorize your insurer to pay a provider directly for covered services, rather than reimbursing you and having you pay the provider yourself.

Balance Billing: When an out-of-network provider bills you for the difference between their charge and what your plan paid. Federal surprise-billing rules limit this in emergencies and certain other situations.
Beneficiary: Anyone covered under a health insurance policy, including the policyholder and any covered dependents.
Benefit Period: The length of time a plan's coverage terms apply, typically one calendar year for individual and employer plans.
Broker (Insurance Broker): A licensed professional who helps you compare and enroll in plans from multiple insurers. Brokers are typically paid by the carrier, not by you, and cannot charge you a fee just to shop.
Bronze Plan: A Marketplace metal tier with the lowest premium and highest cost-sharing (deductibles, copays, coinsurance) of the standard tiers. Suits people who want low monthly costs and use little routine care.

Capitation: A payment model where a provider is paid a fixed amount per patient per month, regardless of how many services that patient uses, common in some HMO arrangements.
Case Management: A service, often included with a health plan, where a nurse or coordinator helps organize care for someone with a complex or chronic condition.
Catastrophic Plan: A Marketplace plan with a very high deductible and low premium, available mainly to people under 30 or with a hardship exemption. Covers essential benefits after the deductible is met.
CHIP (Children's Health Insurance Program): A joint federal-state program providing low-cost coverage to children in families that earn too much for Medicaid but not enough to afford private coverage.
Claim: A request submitted to an insurer for payment of a covered medical service, usually filed by the provider on your behalf.
COBRA: A federal law letting some employees keep their employer group plan after leaving a job, typically for up to 18 months, usually at the full premium cost plus an administrative fee.
Coinsurance: Your percentage share of a covered service's cost after you've met your deductible, commonly 10-40% depending on the plan.
Copayment (Copay): A fixed dollar amount you pay for a covered service, such as $30 for a primary care visit, regardless of the service's actual cost.
Cost-Sharing Reduction (CSR): An income-based Marketplace discount that lowers your deductible, copays, and coinsurance, available only on silver-tier plans to those who qualify.
Covered Services: The medical services, treatments, and supplies a specific plan agrees to pay for, as listed in its Summary of Benefits and Coverage.
Creditable Coverage: Prior health coverage that counts toward reducing or eliminating a waiting period or late-enrollment penalty on a new plan, most often referenced regarding Medicare Part D.

Deductible: The amount you pay for covered services before your plan starts sharing costs. Preventive care is typically covered before the deductible is met.
Dependent: A spouse, child, or other family member covered under someone else's health insurance policy.
Disenrollment: The process of being removed from a health plan, whether voluntarily (switching plans) or involuntarily (non-payment, loss of eligibility).
Durable Medical Equipment (DME): Reusable medical equipment prescribed for home use, such as wheelchairs, walkers, or oxygen equipment, generally covered under a plan's medical benefit rather than its drug benefit.

Effective Date: The date your coverage actually begins and claims can start being paid.
Embedded Deductible: On a family plan, an individual deductible amount built into the larger family deductible, so one person's costs can satisfy their own deductible without the whole family total being met.
Employer-Sponsored Coverage: Health insurance offered through a job, where the employer typically pays part of the premium and the plan is administered as a group health plan. Also called employer coverage or job-based coverage.
Enrollee: A person actively enrolled in a health insurance plan, whether as the policyholder or a covered dependent.
EOB (Explanation of Benefits): A statement from your insurer showing what a provider billed, what the plan paid, and what you owe. It is not a bill itself.
EPO (Exclusive Provider Organization): A plan type requiring you to stay in-network for coverage (like an HMO) but not requiring a primary care doctor or referrals (like a PPO).
Essential Health Benefits: Ten categories of care ACA-compliant plans must cover, including hospitalization, prescription drugs, maternity care, mental health services, and preventive care.
Exclusion: A specific service, condition, or treatment a plan does not cover, listed in the policy documents.

Family Deductible: The combined deductible amount for all family members on one plan, met either through one person's spending or by combining several members' costs, depending on whether the deductible is embedded.
Fee-for-Service: A payment model where providers are paid separately for each individual service performed, as opposed to a flat per-patient rate like capitation.
FSA (Flexible Spending Account): An employer-sponsored account letting you set aside pre-tax money for qualified medical expenses, generally with a use-it-or-lose-it rule each plan year.
Formulary: A plan's list of covered prescription drugs, usually organized into cost tiers.

Gatekeeper: The role a primary care physician plays on HMO and some POS plans, where specialist care generally requires the PCP's referral before it's covered.
Gold Plan: A Marketplace metal tier with higher premiums and lower cost-sharing than silver plans, suited to people who use more regular medical care.
Grace Period: A window after a missed premium payment during which coverage stays active before the plan can be cancelled for non-payment.
Grandfathered Plan: A health plan that existed before the ACA took effect (March 23, 2010) and has kept its original terms since, exempting it from some, but not all, ACA requirements.
Group Health Plan: A health plan offered by an employer or association to its members, typically with the employer contributing toward the premium.
Guaranteed Issue: A rule requiring insurers to offer coverage to anyone who applies during an eligible enrollment period, regardless of health history. ACA Marketplace plans are guaranteed issue.
Guaranteed Renewable: A policy feature meaning the insurer must renew your coverage each term as long as you pay premiums, even if your health changes, though the insurer can still raise rates for the whole class of similar policies.

HDHP (High-Deductible Health Plan): A plan with a higher-than-average deductible, often paired with an HSA. Lower premiums make it a common choice for people with low routine medical usage.
HMO (Health Maintenance Organization): A plan requiring a primary care doctor and referrals to see specialists, with coverage generally limited to in-network providers except in emergencies.
Hospital Indemnity Insurance: A supplemental policy that pays a fixed cash amount per day (or per admission) for a hospital stay, regardless of your actual bill, intended to help with out-of-pocket costs from a primary plan.
HRA (Health Reimbursement Arrangement): An employer-funded account that reimburses employees for qualified medical expenses or premiums, up to an amount the employer sets.
HSA (Health Savings Account): A tax-advantaged account available to people enrolled in an HDHP, used to pay for qualified medical expenses. Unused funds roll over year to year and the account belongs to you, not your employer.

ICHRA (Individual Coverage HRA): An HRA arrangement letting employers reimburse employees for individual market premiums instead of offering a traditional group plan.
In-Network: Providers and facilities that have a contract with your insurer to accept negotiated rates, generally resulting in lower costs to you.
Individual Health Insurance: Coverage purchased directly by a person rather than through an employer, whether through the Marketplace, off-exchange, or a private medically underwritten carrier. See also Private Health Insurance.
Individual Mandate: The former ACA requirement that most Americans carry qualifying health coverage or pay a tax penalty. The federal penalty was reduced to $0 starting in 2019, though a small number of states have their own individual mandates with state-level penalties.
Inpatient Care: Medical care that requires an overnight hospital stay, as opposed to outpatient care.

Late Enrollment Penalty: An additional cost applied in some programs, such as Medicare, when someone enrolls after their initial eligibility window without qualifying coverage in between.
Lifetime Maximum: A cap on how much a plan would pay over a person's lifetime. The ACA banned lifetime maximums on essential health benefits for ACA-compliant plans.
Limited-Duration Plan: A short-term, non-ACA-compliant policy that can medically underwrite applicants and exclude pre-existing conditions. May cost less but typically offers narrower benefits; not a substitute for ACA-compliant coverage for most people.
Long-Term Care Insurance: A separate type of policy covering extended custodial or nursing care, such as in a nursing home or with in-home care, which standard health insurance generally does not cover.

Marketplace: The government-run exchange (HealthCare.gov or a state-based exchange) where individuals and families shop for ACA-compliant plans and apply for premium tax credits.
Maximum Out-of-Pocket: See Out-of-Pocket Maximum.
Medicaid: A joint federal-state program providing coverage to eligible low-income individuals and families. Eligibility rules and expansion status vary by state.
Medically Necessary: Care that meets accepted medical standards for diagnosing or treating a condition. Insurers can deny claims for services deemed not medically necessary.
Medicare: The federal health insurance program primarily for people 65 and older and certain younger people with qualifying disabilities.
Medicare Advantage: A Medicare Part C option where a private insurer administers your Medicare benefits, often bundling in extra benefits like dental or vision, typically with a defined network similar to an HMO or PPO.
Medicare Supplement (Medigap): A private policy that helps cover cost-sharing gaps left by Original Medicare, such as coinsurance and deductibles, purchased alongside Medicare Part A and B rather than replacing them.
Metal Tiers: Bronze, silver, gold, and platinum Marketplace plan categories that describe cost-sharing structure, not the quality of care.
Minimum Essential Coverage: The baseline level of coverage (employer plans, Marketplace plans, Medicaid, Medicare, and others) that satisfies ACA coverage standards.
Modified Adjusted Gross Income (MAGI): The income measure used to determine Marketplace subsidy eligibility and amount, generally your adjusted gross income plus certain items like tax-exempt interest and excluded foreign income.

Network: The group of doctors, hospitals, and facilities that have agreed to a plan's negotiated rates.
Network Adequacy: A regulatory standard requiring a plan's network to include enough providers, within a reasonable distance and wait time, to actually deliver the care the plan covers.
Non-Preferred Provider: An out-of-network or lower-tier provider whose services typically cost more under the plan's cost-sharing rules.

Off-Exchange Plan: An ACA-compliant plan purchased directly from an insurer or broker outside the Marketplace. Off-exchange plans follow the same coverage rules as on-exchange plans but are not eligible for premium tax credits.
Open Enrollment Period: The annual window (generally November 1 to January 15 for the federal Marketplace) during which anyone can enroll in or change ACA-compliant coverage without a qualifying life event.
Out-of-Network: Providers without a contract with your insurer. Care from these providers typically costs more and may not count toward your in-network out-of-pocket maximum.
Out-of-Pocket Maximum: The most you'll pay for covered services in a plan year. Once reached, the plan pays 100% of covered in-network care for the rest of the year.
Outpatient Care: Medical care that doesn't require an overnight hospital stay, such as office visits, many procedures, and same-day surgery.

Plan Year: The 12-month period a plan's benefits, deductible, and out-of-pocket maximum apply to, which may or may not match the calendar year for employer plans.
Platinum Plan: A Marketplace metal tier with the highest premium and lowest cost-sharing of the standard tiers, generally targeting around 90% actuarial value. Suits people who expect to use significant medical care.
POS Plan (Point of Service): A plan blending HMO and PPO features: usually requires a primary care doctor and referrals, but allows out-of-network care at a higher cost.
PPO (Preferred Provider Organization): A plan offering the most network flexibility: no primary care doctor or referrals required, and out-of-network care is covered, though at a higher cost than in-network.
Pre-Existing Condition: A health condition that existed before a new policy's start date. ACA-compliant plans cannot deny coverage or charge more because of one.
Premium: The amount you pay, usually monthly, to keep your health insurance policy active, regardless of whether you use any care.
Premium Tax Credit: An income-based subsidy that lowers your monthly Marketplace premium, either applied in advance to your monthly bill or claimed on your tax return.
Preventive Care: Routine services like annual physicals, immunizations, and screenings, generally covered at no cost on ACA-compliant plans even before the deductible is met.
Primary Care Physician (PCP): Your main doctor for routine and preventive care, often required to be designated on HMO and POS plans.
Prior Authorization: Approval an insurer requires before it will cover certain services, procedures, or medications.
Private Health Insurance: Coverage sold by a private insurance company rather than provided by a government program like Medicaid or Medicare. This includes employer plans, Marketplace plans, and medically underwritten individual policies bought directly from a carrier, sometimes called the private market.
Provider: Any licensed individual or facility delivering medical care, including doctors, specialists, hospitals, and labs.

QSEHRA (Qualified Small Employer HRA): An HRA option for small employers (generally under 50 employees) who don't offer a group plan, letting them reimburse employees tax-free for individual coverage premiums.
Qualified Health Plan (QHP): A plan certified to meet ACA standards for coverage and cost-sharing, eligible to be sold on the Marketplace and to accept premium tax credits.
Qualifying Life Event (QLE): A change in circumstances, such as losing coverage, marriage, divorce, or having a baby, that opens a Special Enrollment Period outside of Open Enrollment.

Referral: Written permission from a primary care doctor to see a specialist, required by some HMO and POS plans before specialist care is covered.
Rider: An add-on to a policy that modifies its coverage, either adding a benefit or excluding one, for an additional cost or condition.
Risk Pool: The full group of people covered under a type of insurance, whose combined premiums and claims determine pricing. A larger, healthier risk pool generally means more stable premiums for everyone in it.

SBC (Summary of Benefits and Coverage): A standardized document every health plan must provide, summarizing coverage, cost-sharing, and exclusions in a consistent format so plans can be compared side by side.
Self-Funded Plan: An employer health plan where the employer pays claims directly (often through a third-party administrator) rather than paying premiums to an insurance carrier.
SHOP (Small Business Health Options Program): The Marketplace channel through which small employers can shop for and offer group coverage to their employees.
Short-Term Health Insurance: Temporary, non-ACA-compliant coverage meant to bridge a gap between other plans. Can exclude pre-existing conditions and essential health benefits, so it's generally best treated as a stopgap rather than primary coverage.
Silver Plan: A Marketplace metal tier in the middle of the cost-sharing spectrum, and the only tier eligible for Cost-Sharing Reductions.
Special Enrollment Period (SEP): A window, typically 60 days, during which you can enroll in or change coverage outside Open Enrollment, triggered by a Qualifying Life Event.
Step Therapy: A requirement to try a lower-cost medication first before a plan will cover a more expensive alternative for the same condition.
Subrogation: An insurer's right to seek reimbursement from a third party (such as another driver's insurance after an accident) after paying your medical claims for an injury someone else caused.
Subsidy: Financial assistance that lowers the cost of coverage, most commonly referring to the Premium Tax Credit or Cost-Sharing Reductions on Marketplace plans.
Supplemental Insurance: Coverage that pays in addition to a primary health plan for specific situations, such as accident, critical illness, or hospital indemnity policies.
Surprise Billing: An unexpected out-of-network bill, most often from ancillary providers (like an anesthesiologist) at an in-network facility. The federal No Surprises Act bans most surprise billing for emergency care and certain other situations.

Telehealth: Medical consultations conducted remotely by phone or video, often covered at a lower copay than an in-person visit.
Tiered Network: A network design where providers are grouped into cost tiers, with lower cost-sharing for using preferred (lower) tiers.
Third-Party Administrator (TPA): A company that processes claims and administers benefits for a self-funded employer plan without bearing the insurance risk itself.

Underwriting: The process an insurer uses to evaluate an applicant's health and risk before issuing a policy, used for medically underwritten private plans but not for ACA Marketplace plans.
Usual, Customary, and Reasonable (UCR): The typical charge for a service in a given geographic area, sometimes used to determine reimbursement for out-of-network care.

Value-Based Care: A payment model that reimburses providers based on patient health outcomes rather than the volume of services performed.

Waiting Period: A span of time after enrollment before certain benefits (commonly major dental or disability benefits) become payable.
Wellness Program: An employer or insurer initiative offering incentives, such as premium discounts, for completing health screenings or wellness activities.

Young Adult Coverage: The ACA rule allowing adult children to stay on a parent's health plan until age 26, regardless of marital status, financial dependence, or student status.

This glossary is for general educational purposes. Definitions describe common industry usage; specific plan documents always govern your actual coverage. Confirm details for your plan in its Summary of Benefits and Coverage or by asking your insurer directly.

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