Purchase orders and inventory are usually discussed separately and they meet at exactly one point: the moment goods arrive. That single act, recording what was delivered, increases stock on one side and enables the three-way match on the other. Recognising it as one event rather than two is what stops it being done twice or not at all.
One act, two consequences
Receiving a delivery against a purchase order line increases the stock of that item and records that the order has been partly or fully satisfied. Systems that separate these ask the same person to do the same thing twice, and the second entry is the one that gets skipped, which is usually the payables one.
Why stock accuracy and match accuracy travel together
An organisation with reliable stock figures almost always has reliable receipts, because the same discipline produces both. Conversely, if your stock counts drift, your match rate is probably suffering for the same reason. Improving the receipt improves both, which is a useful argument when the receipt has no owner.
Where they should stay separate
Valuation and stock accounting are their own discipline, with their own decisions about cost methods and write-downs that belong to your accountant. Payables needs the quantity and the date; it does not need the valuation. Keeping the boundary clear stops a payables project acquiring an inventory accounting scope it cannot deliver.
Questions people ask about purchase order inventory management system
Do we need inventory management to run three-way matching?
No. You need the receipt recorded against the order line. Full inventory management is a larger capability that happens to include it.
What about non-stock purchases?
They still need a receipt, in the sense of somebody confirming delivery. It just does not increase any stock figure.
Which system should own the receipt?
Whichever the person taking the delivery will actually use. Ownership follows usability here, not organisational logic.