coinsurance

noun

co·​in·​sur·​ance ˌkō-ən-ˈshu̇r-ən(t)s 

also -ˈin-ˌshu̇r-

1

: joint assumption of risk (as by two underwriters) with another

2

: insurance (such as fire insurance) in which the insured is obligated to maintain coverage on a risk at a stipulated percentage of its total value or in the event of loss suffer a penalty in proportion to the deficiency

3

: health insurance in which the insured is required to pay a fixed percentage of the cost of medical expenses after the deductible has been paid and the insurer pays the remaining expenses

Coinsurance is not a new idea—Americans who grew up in the era before managed care will remember their parents paying 20% of the costs of office visits, tests, and prescriptions.

—Thomas H. Lee et al.

Examples of coinsurance in a Sentence

Recent Examples on the Web

Insurance plans often require people pay copays, coinsurance and deductibles, the amount a consumer must pay before most coverage kicks in. —Ken Alltucker, USA Today, 27 Mar. 2026

Additionally, 80% said all health care costs -- including premiums, deductibles, co-pays or coinsurance -- are higher. —Mary Kekatos, ABC News, 19 Mar. 2026

Many plans have multiple different deductible amounts, coinsurance rates, copayments and even out-of-pocket maximums, depending on several factors. —Jamie Hartmann-Boyce, The Conversation, 19 Mar. 2026

In some cases, patients would be billed coinsurance and other payments related to the unnecessary equipment, the complaint says. —Sarah Volpenhein, jsonline.com, 6 Mar. 2026

Word History

First Known Use

circa 1889, in the meaning defined at sense 1

Rhymes for coinsurance

• concurrence
• deterrence
• incurrence
• occurrence
• recurrence
• transference
• countertransference

Medical Definition

coinsurance

noun

co·​in·​sur·​ance ˌkō-ən-ˈshu̇r-ən(t)s, -ˈshər- also -ˈin-ˌshu̇r-, -ˌshər- 

: health insurance in which an insurer requires the insured to pay a fixed percentage of the cost of medical expenses after the deductible has been paid and with the insurer to pay the remaining expenses

Coinsurance is not a new idea—Americans who grew up in the era before managed care will remember their parents paying 20% of the costs of office visits, tests, and prescriptions.

—Thomas H. Lee et al., The New England Journal of Medicine

Legal Definition

coinsurance

noun

co·​in·​sur·​ance ˌkō-in-ˈshu̇r-əns, kō-ˈin-ˌshu̇r- 

1

: joint assumption of risk (as by two underwriters) with another

2

: insurance (as fire insurance) in which the insured is obligated to maintain coverage on a risk at a stipulated percentage of its total value or in the event of loss to suffer a penalty in proportion to the deficiency