Legal analysis: VAT duplicate the first and second (i.e., invoice and deduction) to be stamped, stamped with the invoicing person's financial seal or invoice seal. VAT invoices are commercial vouchers, due to the implementation of the invoice purchase tax deduction, the purchaser has to pay VAT to the seller, so it is also a tax certificate, play the seller's tax obligations and the purchaser's input tax amount of the system of legal proof of the role.

Legal basis: "The Chinese people's *** and State invoice management measures implementation rules" Article 28 units and individuals in the issuance of invoices, it must be done in accordance with the number order to fill in, fill in the items complete, the contents of the real, clear handwriting, all the joints a print, the contents of the exact same, and in the invoice and the deduction of the joints with the invoice special seal." The 1st and 2nd copies of VAT (i.e., the invoice copy and the credit copy) should be stamped with the invoicing person's special financial seal or special invoice seal. According to different versions of special invoices, the special financial seal or special invoice seal is stamped on the lower left corner or lower right corner of the special invoice, covering the column of "invoicing unit". Invoice seal using red ink.