7(1)A participator may appeal to the Special Commissioners against an assessment or an amendment of an assessment made on him by notice of appeal in writing given to the Board within thirty days after the date of issue of the notice of assessment or of the amendment.
(2)The notice of appeal shall specify the grounds of appeal, but on the hearing of the appeal the Commissioners may allow the appellant to put forward any ground not specified in the notice, and may take it into consideration if satisfied that the omission was not wilful or unreasonable.
(3)The participator may at any time, if the Board do not object, abandon an appeal instituted by him; and for that purpose he shall notify his desire to do so to the Board who may, within thirty days after being so notified, object by notice in writing to the participator.
(4)Where at any time between—
(a)the giving of a notice of appeal against the assessment or the amendment of the assessment or from a decision ot the Board on a claim under section 33 of the [1970 c. 9.] Taxes Management Act 1970 as applied by paragraph 2 above; and
(b)the determination of the appeal by the Special Commissioners,
the Board and the participator agree on how the assessment, amendment or decision should be varied or on what assessment or determination should be substituted in relation to the chargeable period in question, the same consequences shall ensue as if the Commissioners had determined the appeal to that effect.
(5)If, on the appeal against an assessment or an amendment of an assessment, it appears to the majority of the Commissioners present at the hearing that the assessment or amendment is wrong—
(a)because no, or a smaller, gross profit has accrued for the chargeable period in question; or
(b)because a, or a larger, gross profit has accrued for that period,
the Commissioners shall vary the assessment or amendment in such manner, or substitute such determination, as may be required; and it shall be for the participator to satisfy the Commissioners as to any matters within paragraph (a) above.
(6)Save as otherwise provided by this Schedule (including the provisions applied by paragraph 2 above) the determination by the Special Commissioners of any appeal shall be final and conclusive.
8(1)A participator who has given notice of appeal under paragraph 7 above against an assessment charging him with any duty for a chargeable period may, if he delivered a return for that period as required by paragraph 2 of Schedule 2 to the principal Act, withhold, until the determination or abandonment of the appeal, so much of the duty charged in the assessment as is the smaller of—
(a)the amount of the duty so charged ; and
(b)duty on the difference between—
(i)the aggregate of the consideration received or receivable for oil as stated in the participator's return in pursuance of sub-paragraph (2) of the said paragraph 2 and, subject to sub-paragraph (2) below, the market value of oil so stated ; and
(ii)the aggregate of the corresponding consideration and value as included in the assessment.
(2)Subject to sub-paragraph (3) below, where the market value of all the oil for which a market value is stated in the participator's return is, as stated in that return, less than the value which is produced for that oil by applying to it the average price mentioned in sub-paragraph (4) below, sub-paragraph (1) above shall have effect as if, for the reference to the market value of oil as so stated, there were substituted a reference to the value which is so produced for that oil.
(3)The comparison of values and the substitution required by sub-paragraph (2) above shall, in the case of an appeal by a participator whose return relates both to gas and to other oil, be made separately for the gas and for the other oil.
(4)The average price referred to in sub-paragraph (2) above is the average price at which all oil included in the relevant returns as oil delivered in the period covered by the returns and disposed of in sales at arm's length was so disposed of.
(5)The relevant returns for the purposes of sub-paragraph (4) above are all the returns of all the participators in all oil fields which—
(a)were made for the chargeable period preceding that to which the appeal relates ; and
(b)were delivered before the end of the chargeable period t© which the appeal relates.
(6)Where in determining the gross profit accruing to a participator from a field in a chargeable period the aggregate of the amounts mentioned in section 2(5)(a), (b) and (c) of the principal Act falls to be increased under section 123 of this Act (whether as respects all oil or as respects a particular kind or kinds of oil) the difference mentioned in sub-paragraph (1)(b) above (or, as the case may be, the difference so far as relating to oil of the particular kind or kinds in question) shall be increased by multiplying it by the fraction mentioned in subsection (2) of that section.