Usually, when the vouchers are bound at the end of the month, they are bound in the upper left corner, so the invoice is slightly attached to the upper left corner (if there is 1 invoice, it is directly attached to the upper left corner behind the reimbursement voucher). If there are many, take a sticker and arrange it evenly from the upper left corner to the bottom. For example, some catering invoices are reimbursed at one time. If they are bound together, the binding thickness will be different at the end of the month, which is inconvenient to check).