37(1)This paragraph applies in the case of a supply of electricity, or of gas that is in a gaseous state and is of a kind supplied by a gas utility, affected by—U.K.
(a)a change in the descriptions of supplies that are taxable supplies,
(b)a change in any rate of levy in force,
(c)a change consisting in the rate of levy applicable to the supply ceasing to be, or becoming, the rate that is applicable to half-rate supplies or reduced-rate supplies, or
(d)the change consisting in the transition from 31st March 2001 to 1st April 2001.
(2)For the purposes of this paragraph a supply is affected by a change if the electricity or gas of which it is a supply (“the supplied commodity”) is actually supplied partly before the change and partly after.
However, this paragraph does not apply in the case of a supply that, under paragraph 36(3), is treated as made on 1st April 2001.
(3)If the person liable to account for any levy on the supply so elects—
(a)the rate at which levy is chargeable on any part of the supply, or
(b)any question whether, or to what extent, the supply is a taxable supply,
shall be determined in accordance with sub-paragraph (5) or (6).
(4)An election for determination in accordance with sub-paragraph (6) may be made only where—
(a)there is such a change as is mentioned in sub-paragraph (1)(c), and
(b)all the supplied commodity is actually supplied before the supply is treated as taking place.
(5)Where the election is for determination in accordance with this sub-paragraph, the rules are—
A.Treat the fraction of the supplied commodity actually supplied before the change (“the pre-change fraction”) as supplied by a supply made before the change and treat the fraction of the supplied commodity actually supplied after the change (“the post-change fraction”) as supplied by a supply made after the change.
B.Where the pre-change and post-change fractions are not known (because, for example, there are no relevant meter readings available)—
“the pre-change fraction" is calculated by dividing—
(a)the number of days in the period over which the supply is actually made that fall before the change, by
(b)the number of days in that period; and
“the post-change fraction" is the difference between 1 and the pre-change fraction.
C.If use of the fractions given by rule B would produce an inequitable result, the pre-change and post-change fractions may be derived from a reasonable estimate of the fractions of the supplied commodity actually supplied before and after the change.
(6)Where the election is for determination in accordance with this sub-paragraph, treat the change as taking place immediately after the time at which the last of the supplied commodity was actually supplied.