Article 4 identifies the Persons responsible for the Due Tax. Liability falls first on the Person conducting any activity listed in clause 2 of Article 2 of the Decree-Law. It extends to any Person involved in those activities where the Person who conducted the activity failed to meet his obligation to pay the Tax, as the Executive Regulation specifies. It also falls on the Warehouse Keeper where Excise Goods are released from a Designated Zone and the Payable Tax was not previously paid. Excluded are travellers importing Excise Goods below the Customs Legislation value for non-commercial use, and Stockpilers meeting the Executive Regulation conditions.