Final answer:
The payer of last resort for a patient with multiple sources of insurance is the insurance company that covers the remaining expenses after all other plans have paid.
Step-by-step explanation:
When a patient has multiple sources of insurance coverage, the payer of last resort is the insurance company that is responsible for covering the remaining expenses after all other insurance plans have paid their portion. This insurance company acts as a safety net and ensures that the patient is not left with any out-of-pocket expenses. For example, if a patient has primary insurance through their employer and secondary insurance through a spouse's employer, the secondary insurance would be the payer of last resort.