There is no contract agreement between the buyer and the seller. Invoice is the premise of payment, payment is the main obligation of the contract, and bill is the collateral obligation of the contract. One party cannot use the other party's failure to perform the collateral obligations as a defense against its failure to perform the main obligations of the contract.

It is the seller's obligation to accept the payment and issue the bill, so there is no dispute that the seller should have the obligation to issue the bill. As for whether this can form a confrontation of refusing to pay the purchase price, because the performance of the contract is divided into the obligation of primary payment and the obligation of secondary payment, whether it is the right of defense stipulated in Article 60 of the Contract Law or the right of defense stipulated in Article 67 of the Contract Law at the same time, both parties are required to have consideration for the debts owed. This "consideration" does not require that the debts assumed by both parties are completely equal in value, but only roughly equal. In practice, the payment for goods belongs to the main payment obligation, and the issuance of bills belongs to the subordinate payment obligation. There is no consideration between the main payment obligation and the subordinate payment obligation, so the buyer cannot claim to perform the right of defense at the same time or perform the right of defense first. If the seller does not issue the ticket after the buyer pays, how to protect the legitimate rights and interests of the buyer? There are legal remedies, and buyers can report to the tax authorities to safeguard their legitimate rights and interests.