When Do You Need a Purchase Order? PO Thresholds and Policy

You need a purchase order when a purchase is large enough, recurring enough, or risky enough that you will later want to prove what was agreed. Most US businesses set a dollar threshold, commonly somewhere between 250 and 1,000 dollars, above which a PO is required, and let smaller routine spend run on a card or an expense claim. The test is simple: if you would ever need to dispute the invoice, verify what arrived, or show an auditor the approval, raise a PO.

Last updated July 2026.

Purchase orders get a bad reputation because too many companies apply them to everything, including the 40 dollar box of printer paper, and then wonder why people stop following the process. The point of a PO is control where control is worth having. Below is how to decide where that line sits, and what the alternatives are underneath it. The tool above turns the POs you do raise into clean line-item data, so the control does not come at the cost of hours of typing.

What a purchase order actually buys you

A PO does four things. It records what was agreed, in writing, before the money moves. It creates an approval point, so somebody with authority signs off before the commitment exists. It gives receiving something to check the delivery against. And it gives accounts payable something to match the invoice to, which is the whole basis of the three-way match.

If none of those four things matter for a given purchase, the PO is bureaucracy. If any of them do, it is cheap insurance. That is the entire decision.

When you need a purchase order

How to set a purchase order threshold

The threshold is the dollar figure above which a PO becomes mandatory. There is no universal right answer, and copying another company's number is a mistake, because the correct threshold depends on how much other control you already have. Common practice in US small and mid-sized businesses lands somewhere between 250 and 1,000 dollars, and larger organizations often run higher because expense and card controls catch the small stuff.

Set it by working out what the process costs you. If raising, approving, and matching a PO consumes 20 minutes of staff time, applying it to a 50 dollar purchase is a net loss even before anyone gets annoyed enough to bypass it. Set the threshold high enough that the control is worth its administrative cost, then use cards, expense policy, and spot review to cover what falls below.

Watch for threshold splitting once you set the number. Two orders of 4,500 dollars where one of 9,000 belongs is the most common way a threshold gets defeated, and it is worth reporting on. It is a classic form of maverick spend, and it usually means your approval process is slow rather than that your people are dishonest.

What to use instead of a PO below the threshold

Below the line, the goal is a light control that still leaves a record. Purchasing cards work well for routine, low-value, high-frequency spend, as long as the categories are defined and the statements are reviewed. Expense claims cover one-off buying by individuals. Standing agreements and blanket purchase orders handle repeated buying from the same supplier without raising a fresh PO every time, which is the right answer for consumables you order weekly.

Whatever you choose, decide it explicitly and write it down. Most companies do not have a policy gap so much as an undocumented one, where everyone follows a different rule they believe is correct.

When should a purchase order be issued?

Issue the purchase order after the requisition is approved and the supplier and price are settled, but before the supplier does any work or ships anything. A PO issued after delivery is a formality that fixes nothing, because the commitment already happened. The point of the document is to define the terms while you still have leverage over them.

What comes before a purchase order?

In a standard process, three things. Someone raises a purchase requisition, which is the internal request to buy. Approvers sign off on it against a budget. Then, if the spend is large or the supplier is new, buyers run an RFQ or RFP to select a vendor and settle pricing. The PO is issued only once those are done. The internal request and the external order are frequently confused, and the difference is set out in purchase requisition vs purchase order.

Do you need a purchase order before an invoice?

If you run a PO-based AP process, yes. The PO has to exist first, because the invoice is matched against it. An invoice arriving with no PO on file is what most finance teams call a non-PO invoice, and it has to be routed for manual approval instead of matched automatically. That exception queue is expensive, which is why PO compliance is tracked as a KPI and why unapproved buying shows up as maverick spend.

Does a purchase order need to be signed?

Usually not, though it depends on value and on who is trying to enforce it. Under the Uniform Commercial Code, a contract for the sale of goods for $500 or more generally needs a writing signed by the party you are enforcing against, with a quantity term. A purchase order is normally that writing. In practice most POs move between businesses unsigned, for two reasons.

First, between merchants, a written confirmation that would be good against the sender can bind the recipient too if they had reason to know its contents and did not object in writing within ten days of receiving it. Second, the federal E-SIGN Act gives electronic signatures and records the same legal effect as ink, so an emailed PO with an electronic approval is a signed writing. Suppliers who want certainty ask for a signed order acknowledgment rather than a signed PO, which is the more useful document anyway because it confirms the supplier accepted your terms. The formation question is covered properly in is a purchase order legally binding and the acknowledgment side in purchase order acknowledgment. None of this is legal advice, and thresholds vary by state, so check your own counsel's policy for high-value orders.

What is required on a purchase order?

At minimum: a unique PO number, the buyer and supplier details, a ship-to and bill-to address, the order date, and for each line an item description, quantity, unit of measure, and unit price. Payment terms, delivery date, and a reference to your standard terms and conditions round it out. Every field is broken down in purchase order fields.

Frequently asked questions

When do you need a purchase order?

When the purchase is above your dollar threshold, involves a supplier you buy from repeatedly, has a delivery someone must verify, or will be charged to a grant, job, or client that requires traceability. In short, whenever you might later need to prove what was agreed, check what arrived, or show an auditor who approved it. Small routine spend below the threshold does not need one.

Is a purchase order legally required?

No. There is no US law requiring a purchase order for a business purchase. It is a commercial and internal control document, not a statutory one. Once a supplier accepts it, though, a PO generally forms a binding contract for that order, which is exactly why it is useful: it fixes the price, quantity, and terms in writing before the goods ship.

What is a typical purchase order threshold?

US small and mid-sized businesses commonly require a PO somewhere above 250 to 1,000 dollars, with larger organizations setting higher limits because card and expense controls already cover smaller spend. The right number depends on how much the PO process costs to run. If administering it costs more than the risk it removes, the threshold is set too low.

Do small businesses need purchase orders?

For their larger and recurring purchases, yes. A small business gains the same things from a PO that a large one does: an approval point, an agreed price, and something to match the invoice against. The difference is scale, not principle. What a small business should avoid is applying the PO process to every minor purchase, which creates work without adding control.

What purchases do not need a purchase order?

Routine low-value supplies, utilities, rent, payroll, insurance premiums, and software subscriptions typically do not. Most are already governed by a contract or a fixed agreement, so a PO adds a step without adding control. Small incidental buying is usually better handled with a purchasing card or an expense claim, which cost far less to administer per transaction.

What happens if you skip the purchase order?

You lose the approval point and the matching basis. When the invoice arrives, accounts payable has nothing to check it against, so overbilling, duplicate invoices, and quantity disputes are much harder to catch. It also produces retroactive POs raised after the fact to satisfy the system, which turns approval into a formality and defeats the control entirely.

Getting the process to stick

A PO policy fails for one of two reasons: it applies to too much, or the administrative burden of following it is too high. The first is fixed by setting a sensible threshold. The second is fixed by removing the typing, which is where most of the burden actually lives. Reading supplier POs and confirmations by hand into a spreadsheet or ERP is the step that makes people quietly stop raising them.

That is what this tool removes: upload the purchase order and get the vendor, PO number, dates, and every line back as clean rows in about ten seconds, ready for QuickBooks or whatever system you keep the books in. If you are formalizing purchasing policy generally, it is worth setting up vendor requirements at the same time, since most companies that require a PO from a service vendor also want proof of insurance on file, and tracking those certificates is a separate discipline that tends to get forgotten until a claim.

For the mechanics of the process itself, the purchase order process guide walks the full requisition-to-payment path, and purchase order extraction for accounts payable covers the matching end where the PO finally pays off.