General Rate Act 1967

3 (1) If in any of the successive periods of five calendar years ending respectively with the December last before the coming into force of the relevant lists and the subsequent Decembers falling earlier than two years before the date on which those lists cease to be in force—

(a) the yearly average supply of any statutory water undertakers exceeds or falls short of their yearly average supply in the basic period for those lists ; and

(b) the excess or deficiency is greater than ten per cent. of the last-mentioned average supply,

the cumulo-value for the undertaking as determined for the purposes of those lists shall be adjusted in accordance with the following provisions of this paragraph, and the rateable values of the water hereditaments of the undertaking shall be varied in accordance with paragraph 4 of this Schedule for any rate period beginning fifteen months or more after the end of the said period of five years and ending not later than the date on which the lists cease to be in force or on which a subsequent variation in accordance with the said paragraph 4 takes effect (hereafter in this paragraph and in the said paragraph 4 referred to as a " relevant rate period ").

(2) If there is such an excess as aforesaid, the said cumulo-value shall be increased by an amount which bears to the aggregate of the cumulo-values for all undertakings in England and Wales, as deter-rrrined for the purposes of the relevant lists, the proportion which the excess bears to the yearly average supply of all undertakers therein in the basic period for those lists.

(3) If there is such a deficiency as aforesaid, the said cumulo-value shall be reduced in the proportion which the one average supply mentioned in sub-paragraph (1) of this paragraph bears to the other.

(4) Where the cumulo-value for an undertaking is adjusted under this paragraph, the Commissioners shall, not later than five months before the beginning of the first relevant rate period, furnish to the undertakers and to any rating authority concerned the particulars required for determining the amount of the adjustment.

(5) Where the cumulo-value for any undertaking falls to be adjusted under this paragraph as respects any of the successive periods mentioned in sub-paragraph (1) thereof, then (whether or not the consequential variation of the rateable values of the water hereditaments of the undertaking has taken effect) in the application, in the case of that undertaking, of the foregoing provisions of this paragraph to any subsequent such period—

(a) for the reference in paragraph (a) of the said sub-paragraph (1) to the basic period for the relevant lists there shall be substituted a reference to the preceding or last preceding period of five calendar years as respects which the conditions specified in paragraphs (a) and (b) of the said sub-paragraph (1), or those conditions as modified by this sub-paragraph, are satisfied;

(b) for the references in the foregoing provisions of this paragraph to the cumulo-value for the undertaking as determined for the purposes of the relevant lists there shall be substituted references to the cumulo-value for the undertaking as adjusted or last adjusted under this paragraph.

(6) In the application of the foregoing provisions of this paragraph to the valuation lists in force at the commencement of this Act, references to a period of five calendar years do not include references to any period beginning before the basic period for those lists, but do include references to a period of three or four calendar years beginning with that basic period.