There are few possible scenario for this to happen, and there are effects on inventory value (stock cost), since GRN (Goods Received Note) affects inventory value. In Wavelet, the supplier invoice is automatically created when the users do goods receiving, and as a result, the stock values are updated (with Average Stock calculations). At the point of payment, the stock might have been sold already, hence, performing and purchase return and re-stock in may not be feasible.

When the supplier invoice from the supplier is higher or lower than the invoice recorded in EMP, can choose one of the method:
1) PAYMENT VOUCHER
    With this approach, users will selecting the outstanding invoices when issuing payment voucher, and then charge the difference to a GL Code of choice, for example, Special Discount from Supplier, Supplier Rebate, or Transport Surcharge, Delivery Charges etc. The amount charge to the respective GL Code could be positive or negative. If the GL Code is positive, it adds to the payment voucher amount, and vice versa.

2) CREDIT MEMO & PAYMENT VOUCHER
    Users will create credit memo and charge it to the respective GL Code accordingly. This approach has the advantage of having the real outstanding amount displayed in the outstanding supplier listing, or supplier ageing report. When making payment voucher, users will select both the supplier invoices as well as the supplier credit memo to knock off.