This Quick Reference Guide (QRG) is designed to walk a Customer Billing Specialist or a Customer Contract Specialist through the process of creating a customer invoice adjustment in Workday. There are two ways to adjust an invoice, invoice adjustment and credit and rebill. An invoice adjustment is new transaction with its own document number that is separate from, but linked to, the original invoice and is used to credit (decrease amount due) the amount owed by a customer. If you need to debit (increase the amount due), you should follow the Credit and Rebill procedure. Credit and rebill is a task that allows you to credit an original invoice and then create a new rebill invoice all in a single step.