(a) For the purpose of fixing the tax millage rate to fund the annual budget of each political subdivision or county or independent board of education having the power to levy taxes or set ad valorem tax millage rates on property located within a tax allocation district, which has consented to the inclusion of its property taxes for the computation of tax allocation increments as provided in Code Section 36-44-9, the taxable value of property within a tax allocation district shall not exceed the tax allocation increment base of the district until the district is terminated. Nothing in this chapter shall be construed to freeze the ad valorem tax millage rate of any political subdivision or county or independent board of education consenting to the inclusion of its property taxes as a basis for computing tax allocation increments, and any such rate may be increased or decreased at any time after the creation of a tax allocation district in the same manner and under the same authority that such rate has been previously fixed by such political subdivision or county or independent board of education.

(b) Notwithstanding the provisions of subsection (a) of this Code section and the provisions of any other law to the contrary, including but not limited to those provisions relating to the joint county and municipal sales and use tax provided for in Article 2 of Chapter 8 of Title 48, until a tax allocation district is terminated, a political subdivision or county or independent board of education consenting to the inclusion of its property taxes as a basis for computing a tax allocation increment base within a tax allocation district, as provided in Code Section 36-44-9, may not decrease its ad valorem tax millage rate on taxable property located within that district below the millage rate levied on that property on the last date tax allocation bonds were issued for redevelopment costs of that district.