A copayment (copay) is best defined as:

Why A is correct

A copayment is a flat, fixed dollar amount the insured pays at the point of service, for example, $30 per office visit or $10 per prescription. It is a defined-dollar cost-share rather than a percentage of the bill, which is what distinguishes it from coinsurance. Copayments and coinsurance both reduce the insurer's payout and discourage overuse, but they are calculated differently: one is a stated fee per service, the other a proportional share of expense. Recognizing the fixed-dollar feature of a copay is a standard contract-provision question for medical expense plans (AH-III.A.1d).

Why the other options are wrong

• B) A percentage split of the bill is coinsurance, not a copayment. A copayment is a stated dollar amount per service, for example $30 per office visit, while coinsurance requires the insured to pay a percentage of each covered expense.
• C) The annual out-of-pocket threshold that must be met before coverage begins is the deductible, which is a separate cost-sharing element. The copay is a fixed amount charged per service and is not an annual spending threshold.
• D) The premium is the periodic price paid to maintain the policy in force, while the copay is a per-service charge paid at the time care is received. They are distinct payments and are never substitutes for each other.

Memory hook

Copay = flat fee per visit; coinsurance = percentage of the bill.