When there is an error in a purchase invoice, the supplier normally prefers to issue a credit note rather than cancel the original invoice and issue a replacement.
This is normal and accepted practice. However, an incorrect purchase invoice should not be processed for payment until the credit note has been received.
An invoice from Crab Co for 600 units of product PQR costing $4 each, and the invoice net amount is $2,400 plus sales tax of $480, and a total of $2,880.
On checking the documentation, you find that, although 600 units were ordered and delivered, the delivery note contains a hand-written note that 100 units were delivered in a damaged condition.
You should contact the supplier and explain the problem. The supplier's copy of the delivery note should also include a note that 100 units were delivered in a damaged condition, and if this is the case, the supplier should agree not to charge for the 100 units. The supplier should therefore agree to issue a credit note for $400 plus sales tax of $80, or $480 in total.
The invoice should be retained, but not processed, until the credit note has been received. When the credit note is received, it should be checked and if it is acceptable, the invoice and credit note should be processed together.
When credit notes are received, they should be checked for accuracy.