Part I of the principal Act, except Schedule 7, and Part VIII of the M1 Finance Act 1981 (supplementary petroleum duty) shall apply as if the determination had been made immediately before oil was first won from the field;

where the actual date of the determination is later than the date which by virtue of paragraph (a) above is the end of a chargeable period for the oil field, then as respects that chargeable period sections 33(1) and 34 of the M2 Taxes Management Act 1970 (in their application by virtue of paragraph 1 of Schedule 2 to the principal Act), paragraphs 2(1), 5(1) and 13 of Schedule 2 to the principal Act and paragraph 9 of Schedule 16 to the Finance Act 1981 shall have effect as if any reference to the end of a chargeable period were a reference to the actual date of the determination;

where the actual date of the determination is later than the date which by virtue of paragraph (a) above is the end of a claim period in relation to the oil field, then as respects that claim period paragraph 2(1) of Schedule 5 to the principal Act and paragraph 1(2) of Schedule 6 to that Act shall have effect as if any reference to the end of the claim period in which the expenditure is incurred were a reference to that actual date; and

where the actual date of the determination is later than the date which by virtue of paragraph (a) above is the end of the transfer period, within the meaning of Schedule 17 to the M3 Finance Act 1980, in relation to the oil field, then as respects that transfer period paragraph 3(1) of that Schedule shall have effect as if the reference to the end of the transfer period were a reference to that actual date.

a determination is made under paragraph 5 of Schedule 1 to the principal Act (variation of fields) varying an earlier determination; and

in consequence of that variation an existing oil field is altered to any extent;

any claim falling to be made in accordance with Schedule 5 or 6 to the principal Act in respect of any expenditure incurred before the actual date of the later determination which could not have been made before that determination may be made at any time before the expiry of the period of six years beginning with that date;

section 1 of the M6Petroleum Revenue Tax Act 1980 (payments of tax on account). section 105 of the Finance Act 1980 (advance payments of tax) and paragraph 10 of Schedule 16 to the Finance Act 1981 (payments on account of supplementary petroleum duty) shall not apply in relation to any return made under paragraph 2 of Schedule 2 to the principal Act in so far as it is made by virtue of paragraph (a) above; and

section 139 below (advance petroleum revenue tax) shall not apply in relation to so much of the gross profit as accrues to any person in a chargeable period ending before the actual date of the later determination by virtue only of that later determination.