House Bill No. 521 proposes a constitutional amendment to Article VII, Section 23(C) of the Louisiana Constitution, which pertains to ad valorem property tax millage rates. The amendment allows local taxing authorities to levy a millage rate that is lower than the maximum authorized rate without losing the ability to adjust to the maximum rate from a prior year's reassessment. This change is significant as it provides more flexibility for taxing authorities in managing their millage rates, particularly in years following a reassessment or changes in the homestead exemption.

The proposed amendment will take effect on January 1, 2027, and will apply to all taxable years beginning on or after that date. It will be submitted to voters for approval during the statewide election scheduled for November 3, 2026. The amendment aims to ensure that taxing authorities can maintain lower millage rates while still having the option to increase them to the maximum authorized rate in the future, thereby preventing the permanent loss of this ability if they do not raise their rates in a timely manner.