Wait two days. If it is confirmed by the post office and courier company that it is lost, you can go to your tax office to issue a tax deduction certificate for the lost invoice, and then mail a copy of the list and the invoice account number to the other party. They can take these two things to their tax office to go through the corresponding procedures, and then they can be authenticated and recorded. I've done it once before. It's not complicated. Specifically, you can consult your tax office or administrator, or you can go to the tax office with your invoice account, official seal and tax registration certificate.