Your holding may lie in a single county, but once your interest is pooled to a unit, all interest owners share in production of the unit regardless of county, city, school, or water district boundary. The value is prorated to each district. A taxing entity will choose the most effective method to get the money quickly to start earning interest, make bond payments, pay employees, or whatever. BIlling will be done in the most consistent manner that collects the most money in the speediest manner. Sometimes a district may have a delay in setting their tax rate for various reasons. One district would not want their billing delayed while waiting on another district to resolve their issues. This is just one of the complexities in appraising and collection of ad valorem taxes throughout the state of Texas, an important source of funding for schools, counties etc.