coinsurance

American  

[koh-in-shoor-uhns, -shur-] / ˌkoʊ ɪnˈʃʊər əns, -ˈʃɜr- /

noun

1. insurance underwritten jointly with another or others.

2. a form of property insurance in which an insurer assumes liability only for that proportion of a loss which the amount of insurance bears to a specified percentage of the value of the property.

3. 1. a form of health insurance in which the insured party contributes a specified percentage of the total cost of medical expenses after a deductible has been reached.

   2. the percentage contributed by the insured party.

      My coinsurance is 20%.

---

coinsurance British  

/ -ˈʃɔː-, ˌkəʊɪnˈʃʊərəns /

noun

1. a method of insurance by which property is insured for a certain percentage of its value by a commercial insurance policy while the owner assumes liability for the remainder

2. joint insurance held by two or more persons

---

Etymology

Origin of coinsurance

First recorded in 1885–90; co- + insurance

Example Sentences

Most of those who remained in ACA plans reported larger out-of-pocket healthcare expenses in the form of higher copays, coinsurance or deductibles, according to the survey from health-research nonprofit KFF.

From The Wall Street Journal • Mar. 19, 2026

Money in HSA accounts can be used toward the plan’s deductible, coinsurance, copayments, and for non-covered costs such as eyeglasses.

From Barron's • Nov. 24, 2025

Plus, factor in an emergency fund for home repairs and your Medicare premium, deductibles, coinsurance and copays.

From MarketWatch • Oct. 12, 2025

In fact, insurance companies typically set coinsurance and copay amounts based on a drug's original list price, not the negotiated price.

From Salon • Nov. 22, 2024

Check your insurance policy to know your deductible and any copay or coinsurance should you ever need an ambulance.

From Seattle Times • Nov. 12, 2023