If the invoice is still in the system under accounts payable, create a new invoice with the last fiscal year date for the Vendor but with a negative amount instead. Use the original invoice number as a reference in the new invoice number. Put some notes in the invoice about the rebate. Let me know if this helps.

If the invoice is still in the system under accounts payable, create a new invoice with the last fiscal year date for the Vendor but with a negative amount instead. Use the original invoice number as a reference in the new invoice number. Put some notes in the invoice about the rebate. Let me know if this helps.

What is the date of the rebate check you received?

You can certainly do a negative purchase invoice and a negative payment for the vendor. If this is GST then follow that KB 10754