Tennessee Code Title 56. Insurance § 56-7-610

(a) An enrollee may choose to pay for a healthcare service out-of-pocket from an out-of-network provider. If an enrollee negotiates for a lower cost from an out-of-network provider than the average allowed amount paid by the carrier to a network provider for a comparable healthcare service, and the enrollee pays for the healthcare service out-of-pocket, then the enrollee may send documentation, which may be sent electronically, to the carrier, that provides the following:

(b) A carrier that receives the documentation described in subsection (a) shall count the full amount that the enrollee paid out-of-pocket toward the enrollee's deductible, coinsurance, copayment, or other cost-sharing amount:

(c) The amount counted toward an enrollee's out-of-pocket deductible, coinsurance, copayment, or other cost-sharing amount must not exceed the total amount that the covered person is required to pay out-of-pocket during a contractually agreed upon period of time for healthcare services that are included under the covered person's insurance plan, and does not carry over once a new contract or agreement period for the insurance plan begins.