Purchase order format: the document that starts a transaction, not one that ends it
A purchase order is issued by the buyer, not the seller — which makes it the one document in this set that most small businesses receive rather than send, and the one they have no system for keeping. It records what was ordered, at what price, by when and from whom. Nothing in GST requires you to raise one: the statute mandates the tax invoice, the bill of supply, the delivery challan and credit or debit notes, and a purchase order is none of those. Its value is evidential. When the goods arrive short, or the invoice quotes a rate you never agreed, the PO is what settles the argument. It is also the first leg of the three-way match every accountant runs before paying a bill — order, goods receipt, invoice — and the reason a supplier’s invoice should always carry your PO number.
Frequently asked questions
What is a purchase order?
A purchase order is a buyer-issued document that authorises a supplier to supply a stated quantity of goods or services at a stated price, by a stated date. It is the buyer's record of what was agreed, and it is the document a supplier should quote on their invoice. Because the buyer issues it, most small businesses receive purchase orders far more often than they raise them — and then have no system for keeping the ones they receive, which is where disputes start.
Is a purchase order mandatory under GST?
No. GST mandates specific documents — the tax invoice under Section 31, the bill of supply for exempt goods, the delivery challan under Rule 55, and credit or debit notes under Section 34. A purchase order is not one of them. It is a commercial control rather than a statutory document, and nothing in the return filing depends on it. That is exactly why it is worth having: it exists to resolve commercial disputes, not to satisfy an inspector.
What should a purchase order contain?
The PO number and date, the buyer and supplier names, addresses and GSTINs, a line-item description with HSN or SAC code, quantity, unit, rate and tax rate, the delivery date and place, the payment terms, the place of supply and an authorised signatory. The HSN code and place of supply matter more than they look: they are what let the supplier raise an invoice that matches the order, and a mismatch between the two is the usual reason a payment is held up.
Is a purchase order a tax document? Can I claim input tax credit on it?
No. Input tax credit needs a tax invoice or a debit note carrying the particulars in Rule 46, and a purchase order is neither. A PO shows what you expected to pay, including tax; it does not charge tax and it does not create a credit. If a supplier issues only a purchase order and no tax invoice, there is no ITC and no supply recorded in GSTR-2B.
What is the difference between a purchase order, a quotation and an invoice?
A quotation is the supplier offering a price, and it comes before any commitment. A purchase order is the buyer accepting that price on stated terms, and it authorises the supply. An invoice is the supplier demanding payment after the supply, and it is the only one of the three that carries tax and supports input tax credit. The direction of travel is quotation, then purchase order, then invoice — and each one is issued by a different party in the first two steps.
Do I need a purchase order number series?
Nothing in GST requires one, but you need it for matching. A sequential PO number unique within the financial year is what lets you tie an order to a goods receipt and to the supplier's invoice. Without a series, the three documents can only be matched by description and date, which is exactly the reconciliation that fails when a supplier ships in two parts or invoices a different quantity.
Should GST be shown on a purchase order?
Show it when the supplier is registered, because the order is a budget commitment and the buyer needs the landed cost including tax. Treat the figure as an estimate rather than a charge — the tax that legally applies is the tax on the supplier's invoice, at the rate in force on the date of supply. If the rate changes between order and invoice, the invoice governs and the PO is simply out of date.
What is a three-way match?
It is the check an accountant runs before paying a supplier: the purchase order, the goods receipt note and the tax invoice must agree on description, quantity, rate and tax. Any mismatch is held until it is explained. The PO is the leg that defines what was authorised, which is why a business without purchase orders can only compare the invoice to what someone remembers ordering.