In-network is when you use a medical provider that is within an approved network of physicians. In most cases, covered expenses in-network are covered at a co-payment and/or 100% or 90% coinsurance. The participating provider has agreed to negotiated fees and usually will accept payment from the insurance carrier as payment in full. When utilizing an out of network provider, that provider can charge whatever he deems necessary for their services provided. The insurance carrier will pay their portion, but you as the consumer will be responsible for any balance billing that the insurance carrier does not pay.