Tenn. Code Ann. § 8-8-105: Replacement of sureties

The county legislative body shall demand new sureties from the sheriff from time to time if the old sureties die, remove from the county, become insolvent, or otherwise unable to pay, as it, in its discretion, may judge necessary. A failure on the part of the sheriff to comply with such requirement within thirty (30) days shall vacate the office.