9Subject to paragraphs 7 and 8 above, the duty charged in an assessment made on a participator for any chargeable period, so far as not paid under paragraphs 10 and 11 below, shall be payable by him four months after the end of that chargeable period or, if later, thirty days after the date of issue of the notice of assessment.
10(1)Every participator in an oil field shall, at the time when he delivers to the Board the return for a chargeable period required by paragraph 2 of Schedule 2 to the principal Act—
(a)deliver to the Board a statement showing whether any, and if so what, amount of duty is payable by him under this paragraph for that period in respect of the field; and
(b)pay to the Board a sum equal to the amount of duty, if any, shown in the statement
(2)The statement under sub-paragraph (1)(a) above shall be in such form as the Board may prescribe.
(3)For the purposes of sub-paragraph ((1)(a)) above the duty payable by a participator for any chargeable period in respect of an oil field shall be determined by him by—
(a)calculating the gross profit accruing to him for that period from the field by reference to the particulars included in the return in pursuance of paragraph 2(2) of Schedule 2 to the principal Act (and without regard to sections 123 and 124 of this Act);
(b)making any addition required by section 123 of this Act;
(c)making the reduction required by section 124 of this Act; and
(d)applying to the result the percentage rate at which the duty is chargeable for the period.
(4)The sum paid under sub-paragraph (1)(b) above shall constitute a payment on account of the duty charged in any assessment made on the participator in respect of the gross profit accruing to him for the chargeable period from the oil field ; and if the payment on account exceeds the duty so charged the excess shall be repaid to the participator.
(5)Where a participator gives notice of appeal under paragraph 7 above against an assessment charging duty in respect of which he has made a payment on account, the amount, if any, to be repaid under sub-paragraph (4) above shall be calculated as if the duty charged in the assessment were limited to the duty which he would not be entitled to withhold under paragraph 8 above.
11(1)Subject to sub-paragraphs (4) and (6) below, every participator in an oil field shall, in the third month of each chargeable period and in each of the four succeeding months, make to the Board an advance payment of duty in respect of the field for that period.
(2)The amount of each payment shall be equal to one-fifth of the amount, if any, shown in the statement delivered by the participator under paragraph 10(1)(a) above as payable by him in respect of the field for the last chargeable period.
(3)The aggregate of the advance payments of duty made by a participator in respect of a field for a chargeable period—
(a)shall, to the extent to which it does not exceed the sum which sub-paragraph (1)(b) of paragraph 10 above requires him to pay when delivering his return for that period in respect of the field—
(i)discharge his liability to pay the whole or a corresponding part of that sum ; and
(ii)be treated for the purposes of sub-paragraph (4) of that paragraph as if it were, or were part of, a sum paid by him under sub-paragraph (1)(b) of that paragraph ; and
(b)shall, to the extent to which it exceeds the sum required to be paid as aforesaid, be repaid to him.
(4)If in any month in a chargeable period a participator in an oil field—
(a)has not delivered (otherwise than to the Secretary of State) any of the oil which has been won from the field and disposed of by him at any time in or before that month ; and
(b)has not relevantly appropriated any of the oil which has been so won by him at any such time,
he shall be entitled to withhold the advance payment of duty (if any) in respect of the field for that period which next falls to be made by him after the end of that month.
(5)An advance payment shall not be withheld by virtue of the conditions in sub-paragraph (4) above being fulfilled in any month unless a notice to that effect, in such form as the Board may prescribe, is given to the Board before the end of the next month and—
(a)where the Board are not satisfied with any such notice the powers conferred by paragraph 7 of Schedule 2 to the principal Act (production of accounts etc.) shall be exercisable as if the notice were a return under paragraph 2 of that Schedule ; and
(b)paragraph 8 of that Schedule (penalties) shall apply to an incorrect notice as it applies to an incorrect return under paragraph 2.
(6)No advance payment of duty shall be made in respect of the first chargeable period to which Part VIII of this Act applies or in respect of the first chargeable period for any oil field.
12Certificates of tax deposit issued by the Treasury under section 12 of the [1968 c. 13.] National Loans Act 1968 on terms published on or before 14th May 1979 may be used for making payments of duty; and for that purpose those terms shall have effect with the necessary modifications and as if the duty in or towards the payment of which a certificate is used were due—
(a)in the case of duty payable under paragraph 9 or 10 above, two months after the end of the chargeable period to which it relates ;
(b)in the case of duty payable under paragraph 11 above, at the end of the month in which it is required to be paid.