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Insurance Glossary

52 insurance terms explained in plain English — from EOB to ERISA to external review. Understanding these terms is the first step to winning your appeal.

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Copay (Copayment)
A fixed amount you pay for a covered health service, usually at the time of service. Copays count toward your out-of-pocket maximum.
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Coinsurance
Your share of costs for a covered service, calculated as a percentage of the allowed amount. For example, if your coinsurance is 20%, you pay 20% and your insurer pays 80% after your deductible is met.
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Clinical Criteria (MCG / InterQual)
The evidence-based guidelines insurers use to make medical necessity determinations. Common criteria sets include MCG (Milliman Care Guidelines) and InterQual. You have the right to request a copy of the specific criteria used to deny your claim.
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Coordination of Benefits (COB)
Rules that determine which insurer pays first when you are covered by more than one health plan. The primary plan pays first; the secondary plan may cover some or all remaining costs. COB disputes can result in denied claims.
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CMS (Centers for Medicare and Medicaid Services)
The federal agency that administers Medicare, Medicaid, and the Health Insurance Marketplace. CMS sets coverage standards, publishes denial statistics, and handles complaints about Medicare Advantage plans.
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Coverage Gap (Donut Hole)
A temporary limit on what Medicare Part D will pay for prescription drugs. Once you and your plan have spent a certain amount, you enter the coverage gap and pay a higher percentage of drug costs until catastrophic coverage begins.
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