First, you have to copy the invoice, because finally you have to give it to the customer. After copying, you can use the copy to make an account, and then write a certificate, that is, the invoice bookkeeping link and the certificate that the stub is lost, and then the relevant personnel, preferably the leader, can prove it and put it behind the voucher as an attachment when making an account. Invoice bookkeeping and stub loss are the responsibility of enterprise management and can only be handled in the above way. There will be no fine in tax, because it is an ordinary invoice and does not involve deduction, so don't worry about the fine, just find out the explanation.