There are very few individuals who can afford their healthcare entirely out of pocket. This is why a majority of people utilize health insurance which pays for most of the care. If your medical provider is an in-network provider and accepts the insurance you carry, you are guaranteed to be paying much less than if you were not covered.
But what happens when you receive a bill in the mail for services that you believed were covered by your insurance? This typically occurs when you have a motor vehicle accident and go to your family doctor using your health insurance to pay for the visit. Your health insurance company pays for most of your care, but then the doctor sends you a bill for the uncovered portion. Is that legal?