The purchase order process for small businesses, step by step

When one person does all the buying, the business can run on memory and a stack of emails. Once a second or third person starts ordering, bills arrive that nobody recognizes, prices creep up, and stock is paid for twice or not at all. A simple purchase order process fixes that. It gives every purchase an approval, a written agreement with the supplier, and a record you can match against what arrived and what you were billed. This guide walks through each step, from the first request to the payment, including partial deliveries, backorders and price differences.

Why use purchase orders at all

A purchase order (PO) is a document you send to a supplier that states what you want to buy, how many, at what price, when it should arrive and on what terms. It sounds like paperwork, but it does several useful jobs at once:

Spending is approved before it happens, not discovered when the bill arrives.
Price and quantity are agreed in writing, so you have something to hold the supplier to.
Receiving staff know what to expect, and can spot short or wrong deliveries at the door.
Bills can be checked against the order and the delivery before anyone pays.
Open orders show committed cash, money you have promised to spend but not yet paid, which matters when you plan cash flow.

You do not need a PO for everything. Most small businesses require one for all stock purchases and for anything above a set amount, and leave small routine spending to a company card or petty cash with receipts.

The purchase order process, step by step

The full purchase order process has seven steps. In a small business some of them take seconds, but skipping one entirely is where problems start.

Requisition. Someone identifies a need: stock has hit its reorder point, a machine needs a part, a new hire needs a laptop. They record what is needed, how many, roughly what it will cost and why. This can be a form, a message or a draft PO.
Approval and purchase order. The right person approves the request, based on the amount (see the approval table below). The approved request becomes a purchase order with a unique number, the supplier, item descriptions, quantities, unit prices, delivery address, expected date and payment terms such as Net 30.
Supplier confirmation. The supplier acknowledges the order and confirms price, quantity and delivery date. If anything changes, such as a higher price or a later date, update the PO now, before the goods ship, rather than arguing about it when the bill arrives.
Goods received. When the delivery arrives, count it and check its condition against the PO and the packing slip. Record what actually arrived, not what was ordered. For stock, this is the moment the items should be added to inventory, in the right location.
Vendor bill. The supplier sends an invoice, which you record as a vendor bill. This creates a liability in accounts payable.
Three-way match. Compare the PO, the receiving record and the bill line by line: same items, same quantities, same prices. If all three agree, the bill is cleared for payment. If not, the difference is resolved first.
Payment. Pay by the due date, taking any early-payment discount you have been offered. Terms of 2/10 Net 30, for example, mean a 2% discount if you pay within 10 days, and the full amount within 30. Record the payment against the bill so payables stay accurate.

Two of these steps are internal controls rather than paperwork: approval before ordering, and matching before paying. Ideally the person who approves a purchase is not the only person who receives it and pays for it. In a very small team that is not always possible, so the owner reviewing the payables list and the bank statement each month becomes the backstop.

A sample approval-limit table

Approval limits answer the question "who can say yes to this?" Base them on the total value of the order, not individual lines, and do not allow one large purchase to be split into several small POs to stay under a limit. Here is a starting point for a business with a handful of managers:

Order value	Who approves	Extra requirement
Up to $500	Department lead or designated buyer	None; stock items still need a PO
$500.01 to $5,000	Department manager	Must be within the department's budget
$5,000.01 to $25,000	General manager or owner	Two written quotes for non-routine items
Over $25,000	Owner	Three quotes, plus a cash-flow check before ordering

Your numbers will differ; set them so the owner sees the purchases that matter without becoming a bottleneck for everyday ones. Tying the middle tier to the budget is useful: if a purchase was planned in the annual budget, a manager can approve it; if it was not, it moves up a level. Our guide on how to create a budget for a small business covers how to set those department figures.

Three-way match, partial deliveries and price differences

The three-way match is where the purchase order process earns its keep. Here is a typical example. You order 100 units of a part at $12.00 each. The supplier ships 90, with 10 on backorder, and bills the 90 at $12.50.

Line	Purchase order	Goods received	Vendor bill
Quantity	100	90	90
Unit price	$12.00	n/a	$12.50
Line total	$1,200.00	n/a	$1,125.00

The quantity on the bill matches what was received, so that part is fine. The price does not. At the agreed price, 90 units should cost 90 × $12.00 = $1,080.00, so the bill is $1,125.00 − $1,080.00 = $45.00 too high. Before paying, ask the supplier for a corrected bill or a credit memo, or, if the increase is genuine and you accept it, have the right person approve the change and update the PO. Many businesses set a small tolerance, such as a few dollars or a small percentage, below which a difference can be accepted without escalation.

The 10 units still to come stay open on the PO. When they arrive, receive them against the same order, and match the second bill to that second receipt. Keep three rules in mind for partial deliveries:

Receive what arrived, not what was ordered. Recording 100 when 90 came in overstates stock and lets the full bill pass the match.
Pay only for what was received, unless you agreed to pay in advance.
Close or cancel leftovers deliberately. If you decide you no longer want the backordered units, tell the supplier and close the remaining quantity, so the PO does not sit open for months.

For stock items, the received cost becomes the cost of that inventory layer. If you use FIFO, those units are matched to sales in the order they came in; our FIFO inventory costing guide shows how that flows through to cost of goods sold.

PO numbering and records

Good records make the process auditable and save time when a supplier calls about an old order.

Use sequential, unique numbers, such as PO-1001, PO-1002. Never reuse a number, and keep cancelled POs on file marked as cancelled, so a gap in the sequence has an explanation.
Ask suppliers to quote your PO number on the confirmation, packing slip and invoice. It makes matching much faster.
Keep the trail together: requisition, PO, any changes, the receiving record, the bill and proof of payment. The IRS expects you to keep records that support your deductions, such as invoices and receipts; see IRS Publication 583 on starting a business and keeping records.
Record changes, not overwrites. If the price or quantity changes after approval, note who changed it and why.

In accounting terms, the PO itself creates no journal entry. The entries come later: receiving stock or recording the bill increases inventory or an expense, and creates the payable; paying the bill reduces cash and the payable. That is why a month-end review of goods received but not yet billed, and of bills not yet paid, belongs in your month-end close checklist.

Common purchase order mistakes

Raising the PO after the bill arrives. A PO written to match an invoice approves nothing; it only creates paperwork.
Receiving without counting. Signing the driver's slip without checking quantities makes the three-way match meaningless.
Splitting orders to dodge approval limits. Review POs to the same supplier on the same day if you suspect it.
Leaving old POs open. They overstate committed spending and invite duplicate deliveries.
Paying from the supplier's statement. Pay individual matched bills, not a statement total that may include items you disputed.
Ignoring small price increases. A few cents per unit across hundreds of orders adds up over a year.

Running the purchase order process in one system

The process works on paper, but it is easier when the PO, the receipt and the bill live in the same place and share the same item and vendor records. In BMS Prime, purchase orders, goods receipt and the three-way match sit in the Inventory and Procurement module alongside vendor bills, payments and payables aging. You raise a purchase order, receive the goods into the right warehouse and rack, and match the bill, and stock and its cost follow from the receipt. Users can be given access by module and by action, such as view, enter or approve, which helps you mirror your approval limits. Read our guide to inventory management for small business for the stock side of the picture.

You can see how purchasing connects to accounting and HR on our HR and accounting software page for US small businesses. Inventory and purchasing are included from the Growth plan up, priced per company rather than per user, and every plan starts with a free trial; see pricing. For wider guidance on controlling spending, the SBA's page on managing your business finances is a useful companion.

Frequently asked questions

What is the purchase order process?

It is the sequence a business follows to buy goods or services in a controlled way. Someone requests the purchase, an authorized person approves it, a purchase order is sent to the supplier, the supplier confirms, the goods are counted on arrival, the supplier's bill is checked against the order and the receipt, and only then is the bill paid. Each step leaves a record you can check later.

Is a purchase order legally binding?

In general, a purchase order is an offer to buy, and it can become a binding contract once the supplier accepts it, for example by confirming in writing or by shipping the goods. The exact position depends on the terms on both sides and on state law, so put your standard terms on the order and ask a lawyer about anything large or unusual.

Does a purchase order create an accounting entry?

No. A purchase order is a commitment, not a transaction, so it does not change your ledger. The accounting starts when the goods are received or the supplier's bill is recorded: stock or an expense goes up, and so does accounts payable. Open purchase orders are still worth reviewing, because they show cash you have already promised to spend.

What is the difference between a purchase requisition and a purchase order?

A purchase requisition is an internal request: an employee asks for something to be bought and explains why. It goes to an approver, not to the supplier. A purchase order is the external document sent to the supplier once the request is approved, stating the items, quantities, prices, delivery date and terms. Many small businesses combine the two by approving a draft PO before it is sent.

When should a small business start using purchase orders?

A good time is when someone other than the owner starts buying, when you buy stock regularly from several suppliers, or when bills arrive that nobody remembers ordering. You do not need a PO for every coffee order. Set a dollar threshold, require a PO above it and for all stock purchases, and leave small routine spending to a company card or petty cash.