Tex. Utilities Code § 36.058

(a) Except as provided by Subsection (b), the regulatory authority may not allow as capital cost or as expense a payment to an affiliate for:

(1) the cost of a service, property, right, or other item; or

(2) interest expense.

(b) The regulatory authority may allow a payment described by Subsection (a) only to the extent that the regulatory authority finds the payment is reasonable and necessary for each item or class of items as determined by the commission.

(c) A finding under Subsection (b) must include:

(1) a specific finding of the reasonableness and necessity of each item or class of items allowed; and

(2) a finding that the price to the electric utility is not higher than the prices charged by the supplying affiliate for the same item or class of items to:

(A) its other affiliates or divisions; or

(B) a nonaffiliated person within the same market area or having the same market conditions.

(d) In making a finding regarding an affiliate transaction, the regulatory authority shall:

(1) determine the extent to which the conditions and circumstances of that transaction are reasonably comparable relative to quantity, terms, date of contract, and place of delivery; and

(2) allow for appropriate differences based on that determination.

(e) This section does not require a finding to be made before payments made by an electric utility to an affiliate are included in the utility's charges to consumers if there is a mechanism for making the charges subject to refund pending the making of the finding.

(f) If the regulatory authority finds that an affiliate expense for the test period is unreasonable, the regulatory authority shall:

(1) determine the reasonable level of the expense; and

(2) include that expense in determining the electric utility's cost of service.