Tex. Utilities Code § 36.157

(a) This section applies only to an electric utility, other than a river authority, that operates solely inside ERCOT.

(b) Notwithstanding any other provision of this title, not later than June 1, 2018, the commission by rule shall establish a schedule that requires an electric utility to make periodic filings with the commission to modify or review base rates charged by the electric utility. The schedule may be established on the basis of:

(1) the period since the commission entered the commission's final order in the electric utility's most recent base rate proceeding;

(2) whether the electric utility has earned materially more than the utility's authorized rate of return on equity as demonstrated by earnings monitoring reports; or

(3) other criteria that the commission determines is in the public interest.

(c) The commission shall extend the date for the proceeding required by Subsection (b) by one year on a year-to-year basis if, 180 days before the date the proceeding is required, the electric utility's most recent earnings monitoring report shows the electric utility is earning, on a weather-normalized basis, less than 50 basis points above:

(1) for a transmission and distribution utility, the average of the most recent commission-approved rate of return on equity for each transmission and distribution utility with 175,000 or more metered customers; and

(2) for a transmission-only utility, the average of the most recent commission-approved rate of return on equity for each transmission-only utility.

(d) The commission may extend the date for the proceeding required by Subsection (b) for good cause shown or because of resource constraints of the commission.

(e) This section does not limit the ability of a regulatory authority to initiate a base rate proceeding at any time under this title.