A purchase requisition system exists to move the approval to the only moment when it is still a genuine choice: before anything has been ordered. Once a supplier holds an order, or worse has delivered, approval is a formality performed on a commitment that already exists. Everything else a requisition system does, routing, budgets, catalogues, is secondary to that one shift in timing.
What a requisition captures
Who wants it, what it is, roughly what it will cost, which cost centre carries it and why it is needed. That is enough for an approver to make a decision, and adding much more usually reduces the number of requests actually raised rather than improving the decisions. The most valuable field is the reason, because it is the one an approver reads.
Routing and thresholds
A rule sends the request to the right approver by value and cost centre, and a delegation rule covers absence, which is the single most common cause of a stalled request. Thresholds should reflect the policy the organisation already has rather than inventing a new one, and they should be visible to the person raising the request so nobody is surprised by a second signature.
From requisition to order
An approved requisition becomes a purchase order, and the connection between them should be automatic, because a request approved and then never ordered is a gap somebody will fill by buying it another way. Watching how many approved requisitions never become orders is a good health check on whether the system is being used or worked around.
Questions people ask about purchase requisition system
What is the difference between a requisition and a purchase order?
A requisition is an internal request to buy something. A purchase order is the external commitment sent to a supplier. The requisition is approved; the order is issued.
Do we need requisitions if we already approve purchase orders?
Not necessarily. If your order approval genuinely happens before the order is sent, you already have the control. Requisitions add value chiefly where several people ask for things and purchasing consolidates.
How do we stop people bypassing it?
Make it faster than the alternative and measure how long requests wait. People route around approval processes because of delay far more often than because of policy disagreement.