14(1)A participator may appeal to the Special Commissioners against an assessment or determination made on or in relation to 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 determination.
(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)A participator who has given notice of appeal under sub-paragraph (1) above against an assessment charging him with any tax for a chargeable period may, if he delivered a return for that period as required by paragraph 2 above, withhold, until the determination or abandonment of the appeal, so much of the tax charged in the assessment as is the smaller of—
(a)the amount of the tax so charged ; and
(b)tax 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 that paragraph and, subject to sub-paragraph (4) below, the market value of oil as so stated ; and
(ii)the aggregate of the corresponding consideration and value as included in the assessment.
(4)Subject to sub-paragraph (5) 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 (6) below, sub-paragraph (3) 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.
(5)The comparison of values and the substitution required by sub-paragraph (4) 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.
(6)The average price referred to in sub-paragraph (4) 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.
(7)The relevant returns for the purposes of sub-paragraph (b) 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 to which the appeal relates.
(8)The participator may at any time, if the Board do not object to his doing so, abandon an appeal instituted by him ; and for this 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.
(9)Where, at any time between—
(a)the giving of a notice of appeal against the assessment or determination or from a decision of the Board on a claim under section 33 of the [1970 c. 9.] Taxes Management Act 1970 as applied by paragraph 1 above, and
(b)the determination of the appeal by the Special Commissioners,
the Board and the participator agree on the adjustments that should be made in the assessment or determination and on any consequential adjustments to other assessments or determinations, the Board may make the adjustments agreed on and thereupon the appeal shall be deemed to be abandoned.
(10)If, on the appeal, it appears to a majority of the Commissioners present at the hearing that the assessable profit charged to tax by or stated in the assessment ought to have been larger or smaller, they shall amend the assessment accordingly or substitute for the assessment any determination which could have been made by the Board under paragraph 10 above, but otherwise the assessment shall stand good.
(11)Save as otherwise provided by this Schedule (including the provisions applied by paragraph 1 above), the determination of the Special Commissioners in any proceedings under this Part of this Act shall be final and conclusive.