You can reject any invoice you receive from a supplier.
To Reject an Invoice:
Click Invoices in the Project Menu.
Select List from the Invoices drop-down menu.
The Invoices page appears.
Click the invoice you want to reject.
The Invoice Details page appears.
Click Reject Invoice.
The Reject Invoice page appears.
Enter a reason for rejecting the invoice and click Reject Invoice.
The invoice is rejected and you are returned to the Invoices page where the status of the invoice will have changed to "Rejected".