A blanket purchase order commits to a supplier, a set of prices and usually a total value or a period, with individual deliveries drawn against it as needed. It is the right instrument for repeat buying of the same things, and it removes a great deal of administration. It also introduces one risk that ordinary orders do not have, which is losing track of how much has been drawn.
What it is for
Regular purchasing of the same items from the same supplier: consumables, stationery, materials, recurring services. Rather than an order per delivery, one order fixes prices and terms for the period and each delivery draws against it. Approval happens once at the value of the blanket, which is why the value matters more than any single delivery.
How matching works against one
Invoices are matched against the blanket's agreed prices and against receipts for each delivery, with a running total drawn down. That means line-level receipting matters even more than usual, because there is no per-delivery order to anchor against. Systems that cannot track drawdown turn a blanket order into an unmonitored spending permission.
The risk to watch
Cumulative value exceeding what was approved, one delivery at a time, without anybody noticing. A blanket order needs a visible remaining balance and an alert as it nears its limit, and it needs an expiry. An open-ended blanket order with no drawdown tracking is the procurement equivalent of an unmonitored standing order.
Questions people ask about blanket po
How long should a blanket order run?
Usually a quarter or a year, aligned with how often you would want to revisit prices. Open-ended blankets tend to outlive the agreement they were based on.
What if prices change mid-period?
Revise the order and keep the revision with its date. That is exactly the situation where overwritten orders cause disputes.
Do blanket orders weaken control?
Only if drawdown is not tracked. With a visible remaining balance and an expiry, they concentrate the control at the point where it is most useful.