123Gas levy
(1)Gas levy shall not be payable by any person in respect of any gas unless—
(a)the gas is purchased by that person under a tax-exempt contract or under terms comprised in an excluded oil document; or
(b)the gas is won by that person, and not sold by him under such a contract or under terms so comprised, and is gas to which subsection (2) below applies.
(2)This subsection applies to gas which the British Gas Corporation was on 23rd August 1986 obliged or entitled to purchase (whether immediately or at some future date) under a tax-exempt contract or under terms comprised in an excluded oil document.
(3)In determining whether any gas which is won at any time is gas to which subsection (2) above applies, no account shall be taken of—
(a)any future variation of rights and liabilities under a tax-exempt contract, or under terms comprised in an excluded oil document, other than one effected by the exercise of an existing option; or
(b)any future termination of such rights and liabilities other than one occurring before 5th March 1990.
(4)In this section—
“excluded oil document” means a document which on 1st April 1980 was treated for the purposes of paragraph (a) of subsection (1) of section 10 of the Oil Taxation Act 1975 as containing the whole or part of a contract for the sale of excluded oil as defined in that subsection;
“existing option” means an option granted before the commencement of this section;
“future”, in relation to a variation or termination, means effected or occurring after that commencement;
“tax-exempt contract” has the same meaning as the [1981 c. 3.] Gas Levy Act 1981;
“termination” means any termination, whether occurring by effluxion of time, by the exercise of an existing option or otherwise.
(5)This section shall be deemed to have come into force on 24th August 1986.