paper invoices can be issued for catering. according to relevant regulations, after purchasing goods, consumers have the right to ask for invoices from merchants, and merchants are also obliged to issue invoices. Invoices and receipts that do not meet the requirements shall not be used instead of official invoices, nor shall they be used as financial reimbursement vouchers, and any unit or individual has the right to refuse them. No matter what reason the merchant has, it is illegal not to invoice.