(a) Refunds.

(1) The public utility whose proposed increased rates or charges were suspended shall refund at such time in such amounts and in such manner as required by final order of the Commission the portion of any increased rates or charges found by the Commission in that suspension proceeding not to be justified, together with interest as required in paragraph (a)(2) of this section.

(2) Interest shall be computed from the date of collection until the date refunds are made as follows:

(i) At a rate of seven percent simple interest per annum on all excessive rates or charges held prior to October 10, 1974;

(ii) At a rate of nine percent simple interest per annum on all excessive rates or charges held between October 10, 1974, and September 30, 1979; and

(iii)

(A) At an average prime rate for each calendar quarter on all excessive rates or charges held (including all interest applicable to such rates or charges) on or after October 1, 1979. The applicable average prime rate for each calendar quarter shall be the arithmetic mean, to the nearest one-hundredth of one percent, of the prime rate values published in the Federal Reserve Bulletin, or in the Federal Reserve's “Selected Interest Rates” (Statistical Release H. 15), for the fourth, third, and second months preceding the first month of the calendar quarter.

(B) The interest required to be paid under clause (iii)(A) shall be compounded quarterly.

(3) Any public utility required to make refunds pursuant to this section shall bear all costs of such refunding.

(b) Reports. Any public utility whose proposed increased rates or charges were suspended and have gone into effect pending final order of the Commission pursuant to section 205(e) of the Federal Power Act shall keep accurate account of all amounts received under the increased rates or charges which became effective after the suspension period, for each billing period, specifying by whom and in whose behalf such amounts are paid.

[44 FR 53503, Sept. 14, 1979, as amended at 45 FR 3889, Jan. 21, 1980; Order 545, 57 FR 53990, Nov. 16, 1992; 74 FR 54463, Oct. 22, 2009]