Article 40 provides a specific rule for determining the taxable value of supply for vouchers. Under this provision, the value is not the face value of the voucher but is calculated as the net difference between the consideration received by the voucher's supplier and the advertised monetary value of that voucher. This calculation method ensures that the tax is levied on the margin or fee earned by the supplier for issuing the voucher, rather than its total redeemable amount. This framework is essential for businesses engaged in selling or distributing vouchers as part of their commercial activities.