A purchase requisition is an internal request: somebody asking permission to buy something before any supplier has been contacted. Its entire value is in the timing. Approving before a commitment exists is a decision that can go either way at no cost; approving afterwards is a formality performed on something that has already happened.
What it asks and who answers
What is wanted, roughly what it costs, which budget carries it, when it is needed and why. A budget holder answers, against a threshold taken from your existing delegated authority. The question is whether the organisation should spend this money, which is different from whether the price is right or the invoice is correct.
How it differs from the order
The requisition is internal and commits nobody. The purchase order is external and commits you once the supplier acts on it. An approved requisition becomes an order raised by whoever handles buying, carrying its approval with it so the chain from request to invoice remains traceable when somebody asks about it later.
Why speed is a control question
A requisition process that takes days sends urgent spend to a company card instead, and that spend arrives later as an invoice with no order, no match and a full manual approval. So the elapsed time of the requisition process directly determines how much of your spending is controlled at all, which makes speed a control metric rather than a convenience.
Keeping it usable
Five fields, a named approver with automatic cover, escalation after a defined period, visible status for the requester, and a prompt answer either way with a reason if declined. None of these is a feature; all of them are the difference between a process people follow and one they route around.
Questions people ask about what is purchase requisition
Is it legally binding?
No. It is internal. The commitment to a supplier is made by the purchase order or a contract, not by the request.
Do all purchases need one?
Most organisations set a value threshold. Setting it deliberately is better than letting people guess, which produces inconsistent practice and awkward conversations.
Who should raise one?
Whoever needs the goods or service, which is usually somebody outside finance, and that is exactly why the form must be short.