Some invoices are so complex, involving the entry of purchase order numbers, many line items, price discounts and other credits, that it is difficult to create a perfect invoice. This is a particular problem when employee expenses are sent to a customer for reimbursement and the submitted expenses are incomplete or inaccurate. When sent to the customer, they end up being the proofreader, and reject the invoice until the company goes through more delays and eventually issues an accurate invoice. The time delay can be substantial.
The solution is to assign a second person to be the invoice proofreader. This person does not create the invoice, and so has an independent view of the situation and can provide a more independent view of invoice accuracy. Since this can introduce some delay into the invoice creation process, proofreading can be limited to only the larger invoices, or to invoices sent to those customers most apt to comb through invoices looking for mistakes.