What can vary ?

1. The supplier does not have the stock now = sends it later with another purchase order to you
2. The price on the supplier invoice is not the same as the purchase order and this is not discovered until after the stock has been received

For landed cost variations to expected landed cost prices - see Landed Costing

Stock does not arrive

If a stock item does not arrive on a purchase order - count the received qty as zero = the purchase order will then be processed normally.  The invoice will match up with the shipment

More stock arrives than expected

Count the stock that arrived - the counted will be greater than the ordered qty.  The system will prompt if the invoice includes the additional stock - or if it was sent as free stock

Unexpected Stock items arrive

Perhaps they were ordered on a previous purchase order that was short shipped.  Use the "Add Item" button on the stock receipt to enter the new item and qty, it will have a zero ordered qty - the invoice will be created for the counted quantity

The invoice is a different price each to the purchase order after stock has been counted and received

The invoice price variance will be allocated by the system to a control account "Purchase Price Variance" and the stock will NOT be revalued.