4(1)Where it appears to the Board that, in accordance with Part VIII of this Act, a gross profit has accured to a participator in a chargeable period from an oil field, they shall make an assessment to the duty on the participator and give him notice of the assessment.
(2)Where it appears to the Board that, in accordance with Part VIII of this Act, no gross profit has accrued to a participator in a chargeable period from an oil field, they shall make a determination to that effect and give him notice of the determination.
(3)A notice of assessment shall state that the participator may appeal against the assessment in accordance with paragraph 7 below.
(4)After the service of the notice of assessment or the notice of determination the assessment or determination, as the case may be, shall not be altered except in accordance with the provisions applied by paragraph 2 above or the subsequent provisions of this Schedule.
5(1)Where a participator has under paragraph 2 of Schedule 2 to the principal Act delivered to the Board a return for a chargeable period and the Board are satisfied that the information given in the return is correct in so far as it is material for the purpose of computing his gross profit (if any) for that period, the Board shall (in so far as the computation falls to be made by reference to the matters dealt with in the return) make the assessment or determination under paragraph 4 above in accordance with the return.
(2)Where the Board are not so satisfied in relation to a participator's return or a participator fails to deliver to the Board a return for a chargeable period as required by the said paragraph 2, the Board shall, in so far as the computation of his gross profit (if any) for that period falls to be made by reference to the matters which were dealt with in the return or, as the case may be, ought to have been dealt with in a return, make the assessment or determination under paragraph 4 above to the best of their judgment.
(3)Nothing in sub-paragraph (2) above or in paragraph 5 of Schedule 2 to the principal Act shall be taken, in a case where the participator has delivered a return as to which the Board are not satisfied as mentioned in sub-paragraph (1) above, to prevent the Board from basing their assessment or determination on the participator's having had an interest in oil won and saved from the field different from that on which he based his return.
6(1)Where it appears to the Board—
(a)that the gross profit charged to the duty by an assessment ought to have been larger or smaller; or
(b)that for any period they ought to have made an assessment to the duty instead of a determination under paragraph 4(2) above or such a determination instead of an assessment to the duty,
the Board may make any such assessment or determination or any such amendment of an assessment as may be necessary.
(2)Where under this paragraph the Board make an assessment or determination or amend an assessment, they shall give notice thereof to the participator concerned; and sub-paragraphs (3) and (4) of paragraph 4 above shall apply in relation to any such assessment, determination or amendment as they apply in relation to an assessment or determination under that paragraph.