With health insurance, what if the provider does not submit the claim before the window for doing so closes?

For example, on a date the provider provided a service, but failed to properly submit the claim for insurance before the window for doing so closes. Does the person who received the service then have to pay the provider, or does the provider forfeit payment for not properly submitting the claim?
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It depends on the provider's contract with the insurer. Most contracts, with an IN NETWORK provider, say that the provider has to "eat" the bill - and can't charge the patient. But if it's not in network, or that provision isn't in the contract, then the patient is on the hook for the full amount.
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