Tennessee Code Title 20. Civil Procedure § 20-12-144

(c)(1) The clerk may retain up to fifty percent (50%) of any portion of the court costs or litigation taxes, or both, which have not been paid within six (6) months after the adjudication of a civil case in accordance with any in-house collection procedure or, if an agent is used, for the collection agent, which may be allocated from each payment made on the amounts owing for such civil costs and taxes. The proceeds from any in-house collection shall be treated as other fees of the office.

(2) On or after January 1, 2015, if an agent is used, the agent's collection fee shall be added to the total amount owed. The agent's collection fee shall not exceed forty percent (40%) of any amounts actually collected, which may be allocated from each payment made on the amounts owing for such civil costs and taxes.