Article 5 Method of calculating the relief
Where article 3 of this Order applies, the tax chargeable on the importation shall be calculated by—
excluding the residue of the tax paid in a member State from the value of the goods on which tax is chargeable; and
deducting the residue of the tax paid in a member State from the tax which, but for this Order, would be chargeable on the importation.
The residue of tax referred to in paragraph (1) above shall be—
where the value of the goods has decreased in the period between the last taxable transaction and exportation, the amount of tax paid in a member State less the percentage by which the value of the goods has decreased;
in any other case, the whole amount of the tax paid in a member State.
Where any sum relevant to this Order is expressed in a currency other than sterling that sum shall be converted into sterling at the rate of exchange in force at the time the tax becomes chargeable in accordance with the Community rules applicable to valuation for customs purposes.
Where the calculation referred to in paragraph (1) above produces a negative amount there shall not be any refund of tax.