Which term refers to the portion of the bill that the insured must pay for a medical service?

The term that refers to the portion of the bill that the insured must pay for a medical service is copayment. A copayment is a fixed amount that an insured individual pays for specific medical services at the time of the service, while the insurance covers the remaining cost. This structure allows patients to share the cost of their healthcare, making it a common practice among various health insurance plans.

In contrast, a deductible refers to the amount that a policyholder must pay out-of-pocket before their health insurance begins to cover costs, which differs from the concept of a copayment. Disease management generally pertains to programs aimed at managing chronic conditions and improving patient outcomes and does not specifically address immediate payment responsibilities. A subsidy involves financial assistance that helps patients afford health insurance premiums but is not related to the direct payments made at the time of service. Thus, copayment is the most accurate term in this context, as it specifically denotes the patient's financial responsibility for individual medical visits or treatments.