What is a backorder?

A backorder is an accepted order you cannot currently fulfill, held open until stock arrives rather than cancelled. It preserves the sale and the customer relationship, and it commits you to a delivery date that depends on a supplier. Retail purchase orders are usually not backorderable — an unfillable line is a short shipment.

Backorders need an expected date attached and inventory reserved against them on arrival. Incoming stock that gets sold to new orders while older backorders wait is the failure mode.

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