Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 64K, § 11

When a dealer purchases, acquires, transports, or imports into the Commonwealth marihuana or controlled substances on which a tax is imposed by section eight and, if the indicia evidencing the payment of the tax has not already been affixed thereto, the dealer shall have them permanently affixed on the marihuana or controlled substance immediately after receiving such marihuana or controlled substance.  Each stamp or other official indicia shall be used only once.

Taxes imposed upon marihuana or controlled substances by this chapter are due and payable immediately upon acquisition or possession in the Commonwealth by a dealer.