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

Many also must pay coinsurance, which is a percentage of a total drug's cost. —Ken Alltucker, USA Today, 25 Apr. 2025

In 2020, 10% of those patients faced coinsurance for Tier 3 drugs; just four years later, more than 70% faced such coinsurance. —Peter Ubel, Forbes.com, 23 Apr. 2025

Plans typically combine coverage for hospital and outpatient care as well as medications, while eliminating the 20% coinsurance requirement and capping beneficiaries’ annual out-of-pocket costs. —Joshua P. Cohen, Forbes.com, 10 Apr. 2025

But without a Medigap policy to supplement original Medicare, the beneficiary has to pay for all the gaps in Medicare Part B. The out-of-pocket cost can be substantial, because a major gap is the 20% coinsurance amount on most covered care. —Bob Carlson, Forbes, 21 Dec. 2024

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