A purchase order (PO) is a formal document issued by a buyer to a supplier, confirming the intention to purchase specific goods or services under agreed terms. It specifies exactly what is being ordered, in what quantities, at what price and where it should be delivered. Once the supplier accepts the PO, it becomes a legally binding agreement between both parties.
What should a purchase order include?
There is no federal format requirement for purchase orders in the US, but a detailed PO prevents misunderstandings, reduces errors and gives both parties a clear reference point for the entire transaction.
#When and why is a purchase order used?
A purchase order is issued by the buyer before goods are shipped or services begin. It formalizes the agreement and creates a traceable paper trail. Common use cases include:
Cost control and budgeting – A PO commits a specific dollar amount before the expense is incurred. This allows your finance team to track committed spend against budgets in real time, preventing overspending before it happens.
Legal protection – Once accepted by the supplier, a PO is a binding contract. It defines what was agreed – scope, quantities, pricing, delivery date – and gives both parties clear grounds if a dispute arises.
Supplier management – POs create a documented history with each vendor. Over time, this data helps you negotiate better terms, evaluate supplier reliability and consolidate purchases.
Audit and compliance – The IRS expects businesses to maintain records that support income and expense items on their tax returns. POs are a key part of that documentation trail, showing that expenses were authorized, received and properly invoiced.
Do sole proprietors and freelancers need purchase orders? For very small businesses or solo operators, formal POs may feel like overkill – and for simple, one-off purchases, they often are. But once you are managing multiple suppliers, recurring orders or any project with a budget, POs quickly pay for themselves in fewer billing disputes, faster payment approvals and cleaner books at tax time.
Set a PO approval threshold – require manager or finance approval for POs above a certain dollar amount (e.g. $500, $1,000 or $5,000 depending on your business size). This prevents unauthorized spending.
Always specify FOB terms – who bears the risk (and freight cost) during shipping is one of the most common sources of disputes. State FOB Origin or FOB Destination clearly on every PO.
Track open POs regularly – an open PO represents committed but unspent money. Review open orders monthly to catch stale or forgotten POs that should be closed or canceled.
Keep POs for at least 3 years – they are part of your IRS-required documentation. If income is underreported by more than 25 %, the retention period extends to 6 years.
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