Texas Tax Code - TAX § 23.011. Cost Method of Appraisal

(1) use cost data obtained from generally accepted sources;

(2) make any appropriate adjustment for physical, functional, or economic obsolescence;

(3) make available to the public on request cost data developed and used by the chief appraiser as applied to all properties within a property category and may charge a reasonable fee to the public for the data;

(4) clearly state the reason for any variation between generally accepted cost data and locally produced cost data if the data vary by more than 10 percent;  and

(5) make available to the property owner on request all applicable market data that demonstrate the difference between the replacement cost of the improvements to the property and the depreciated value of the improvements.