Some, if not most, health care providers in the United States will agree to bill the insurance company if patients are willing to sign an agreement that they will be responsible for the amount that the insurance company doesn't pay. The insurance company pays out of network providers according to "reasonable and customary" charges, which may be less than the provider's usual fee. The provider may also have a separate contract with the insurer to accept what amounts to a discounted rate or capitation to the provider's standard charges. It generally costs the patient less to use an in-network provider.
Medicare Levy Surcharge: People whose taxable income is greater than a specified amount (in the 2011/12 financial year $80,000 for singles and $168,000 for couples) and who do not have an adequate level of private hospital cover must pay a 1% surcharge on top of the standard 1.5% Medicare Levy. The rationale is that if the people in this income group are forced to pay more money one way or another, most would choose to purchase hospital insurance with it, with the possibility of a benefit in the event that they need private hospital treatment – rather than pay it in the form of extra tax as well as having to meet their own private hospital costs.