House Bill 308 amends Tennessee Code Annotated to allow counties with populations over 900,000 to levy a sales tax at a rate of three and three-quarters percent (3.75%). This new tax rate can be implemented through a resolution by the county's legislative body and is intended to generate revenue exclusively for the construction of a new county jail or to retire related debt. The bill stipulates that the revenue from this tax increase must be allocated for these purposes for a period of eight years or until the debt is fully retired, whichever comes first. After this period, the tax rate will revert to two and three-quarters percent (2.75%).

Additionally, the bill specifies that any revenue generated from the previous tax rate of two and one-quarter percent (2.25%) to the new rate of two and three-quarters percent (2.75%) must be allocated to the county sheriff's department for various expenses. This allocation is required to be in addition to other state and local funds provided to the department, ensuring that the new revenue does not replace existing funding. The act takes effect upon becoming law, emphasizing its urgency for public welfare.