An assessment related to the cost of an improvement that is to be constructed is not valid unless the commissioners court:

1. (1) makes or causes to be made an estimate of the cost of the improvement; and
2. (2) includes the estimate in a published or mailed notice required by Section 286.007.

Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.