Tennessee Code Title 24. Evidence and Witnesses § 24-4-101

(a) A witness in a court of record shall receive compensation of one dollar ($1.00) per day for each day's necessary attendance. When a witness resides at a distance greater than ten (10) miles, such witness shall receive four cents (4¢) per mile for going to and returning from court, and tolls and ferriages as allowed by law. Mileage, tolls and ferriages shall be allowed only for one (1) trip going and returning during the term of any court, unless the witness is discharged by the parties, to return, and does return, upon a given day.

(b) Witnesses in courts of record attending under subpoena in a civil matter shall receive upon request to the clerk thirty dollars ($30.00) per day for such attendance. In addition, when such witness resides at a distance of greater than ten (10) miles from the court, the witness shall, upon request to the clerk, also receive reimbursement for travel expenses for each mile traveled when going to and returning from such court at the rate allowable under the state comprehensive travel regulations in effect at that time. All such compensation and reimbursement shall be taxed as cost.

(c) No witness attending any court of record under subpoena in a civil matter shall be entitled to receive the witness compensation and travel expense reimbursement provided for by subsection (b) until such compensation and reimbursement have been taxed and collected as cost by the clerk of the court of record in which such witness has appeared while under subpoena. Nothing in this subsection (c) shall be construed as preventing the party causing a subpoena to be issued from advancing travel expenses or attendance fees to witnesses.