SB 1051 modifies the calculation of ad valorem tax rates when a property owner appeals an appraisal review board's valuation decision. It introduces the concept of "anticipated substantial litigation" to account for tax protests involving high-value properties and allows for an adjustment in a taxing unit’s total taxable value when such appeals are pending. The bill establishes procedures for taxing units to document contested values, ensures transparency in tax rate calculations, and mandates that this information be incorporated into county property tax databases.