Final answer:
The difference between a nurse practitioner's charge of $45 for an office visit and the insurance company's payment of $34 is a contractual allowance.
Step-by-step explanation:
The difference between a nurse practitioner's charge of $45 for an office visit and the insurance company's payment of $34 is a contractual allowance. A contractual allowance is the difference between the provider's charge and the insurance company's reimbursement, and it represents the amount that the provider agrees to write off or not collect from the patient.