Under current law, leaseholds and other possessory interests in exempt property are taxable and must be listed in the appraisal records in the name of the owner of the possessory interest if the duration of the interest is at least one year. A leasehold or other possessory interest in exempt property used as an aid or facility incidental to or useful in the operation or development of a port or waterway or in aid of navigation-related commerce is exempt under Tax Code 25.07 (b)(6)(B); however those activities are not defined in statute. There could be an indeterminate cost to local taxing units and to the state through operation of the school funding formulas to the extent that local taxing units currently levy a property tax on leaseholds and possessory interests in property used in the activities as defined by the bill. Insufficient information is available about the extent of this practice and standards in determining qualification as navigation-related commerce vary across the state. As a result, the cost cannot be estimated.