Tex. Finance Code § 341.203: COMPUTATION OF REVISED CEILING OR BRACKET.

(a) The amount of a revised ceiling or bracket is computed by:

(1) dividing the reference base index into the consumer price index at the end of the preceding year;

(2) computing the percentage of change under Subdivision (1) to the nearest whole percent;

(3) rounding the result computed under Subdivision (2) to the next lower multiple of 10 percent unless the result computed under Subdivision (2) is a multiple of 10 percent in which event that result is used; and

(4) multiplying the reference amount of the ceiling or bracket provided by this subtitle by the result under Subdivision (3).

(b) If the consumer price index is revised, the revised index shall be used to compute amounts under this section after that revision takes effect. If the revision changes the reference base index, a revised reference base index shall be used. The revised reference base index shall bear the same ratio to the reference base index as the revised consumer price index for the first month in which it is available bears to the consumer price index for the first month in which the revised consumer price index is available.

Acts 1997, 75th Leg., ch. 1008, Sec. 1, eff. Sept. 1, 1997.