A quote is created by the seller. It describes what the seller is willing to supply, at what price, and on which terms. A purchase order, or PO, is created by the buyer. It tells the supplier what the buyer has authorised for purchase.
In a common B2B workflow, the quote comes first and the PO follows approval. A PO should not be treated as a harmless copy of the quote: it may contain different dates, quantities, billing details, or standard terms. Compare the two before starting work.
This article provides general commercial information, not legal or accounting advice. Contract rules vary by jurisdiction and transaction.
Quote vs purchase order
| Quote | Purchase order | |
|---|---|---|
| Created by | Seller or service provider | Buyer or procurement team |
| Main purpose | Offer scope, price, and commercial terms | Authorise and record a purchase |
| Typical timing | Before the buyer decides | After internal approval, usually before supply begins |
| Main reference | Quote number and revision | PO number and line items |
| Acceptance | The buyer may accept the quote | The seller must still check whether the PO matches the agreement |
| Invoice role | Supports the agreed price | Often must be quoted on the invoice for matching and payment |
The titles describe different jobs. Neither title alone decides whether a contract has been formed. Wording, incorporated terms, communication, conduct, and applicable law all matter.
A typical quote-to-PO workflow
- The buyer asks for a price or proposal.
- The seller sends quote Q-2026-041 with scope, exclusions, price, dates, and terms.
- The buyer reviews it and completes internal approval.
- The buyer issues purchase order PO-7842.
- The seller compares the PO with the accepted quote and resolves any difference.
- Work or delivery begins once the agreed starting conditions are met.
- The seller issues the required invoice and includes the PO number if the buyer requires it.
Some buyers skip a formal PO. Others operate a strict “no PO, no pay” policy and will not process an invoice without a valid number. Ask about the process before the intended start date, especially when dealing with a large organisation or public body.
Keep the approval trail clear
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What to check when the PO arrives
Do not check only the total. Compare:
- legal names and billing entity;
- quote and PO references;
- services, quantities, and line descriptions;
- currency, tax treatment, and expenses;
- delivery or milestone dates;
- payment amount and payment period;
- cancellation, warranty, liability, and ownership terms;
- documents or portals required for invoicing.
A small description change may be harmless. A different payment period, an extra deliverable, or new buyer terms may not be.
Example:
Quote Q-2026-041: €6,000, 40% deposit, balance on delivery, two review rounds.
PO-7842: €6,000, payment 60 days after final delivery, unlimited changes under the buyer's standard terms.
The number matches, but the agreement does not. Reply before accepting the PO or beginning performance. State the differences and ask for a corrected PO or an explicit written agreement on the controlling terms.
Is a purchase order acceptance of a quote?
It can be evidence of acceptance when it matches the quote, but that is not a universal rule. A PO may also operate as the buyer's offer, particularly when it introduces its own terms. Starting work or delivering goods can have legal consequences even without a signature.
Use the same checks in every transaction:
- make the quote number and revision visible;
- ask the buyer to reference that version on the PO;
- compare the documents before performance;
- resolve conflicting terms in writing;
- keep the final record together.
For the broader contract question, see when a quote may become legally binding.
Purchase order vs invoice
A PO is not an invoice. The buyer uses it to authorise and track the purchase; the seller issues an invoice to request and record payment under the applicable invoicing rules.
The invoice commonly includes:
- the buyer's PO number;
- the seller's invoice number;
- the relevant PO line or project reference;
- the supplied items or milestone;
- the amount, currency, and tax details;
- the payment instructions.
If the invoice does not match the PO, accounts payable may return it even when the work was properly completed. Check whether the buyer requires one invoice per PO, separate invoices per line, a supplier portal, or evidence of delivery.
A proforma invoice has a different purpose: it previews invoice-style details before the final invoice. Do not use a proforma to hide an unresolved difference between the quote and PO.
What if no PO arrives?
First check the agreed starting conditions. If your quote says work begins after a valid PO, wait for it. If the client said a PO was required but has not supplied one, send a short operational message:
We are ready to begin under quote Q-2026-041. Your onboarding notes say that a valid purchase order is required before work starts and for invoice processing. Please send the PO referencing the quote, or confirm in writing that no PO is required for this project. We will confirm the start date once that point is resolved.
Do not invent a PO number, use another project's number, or assume that a manager's email overrides the buyer's purchasing rules.
Keep the document chain traceable
Use references that let another person reconstruct the transaction:
- Q-2026-041 rev. 2 — seller's approved quote;
- PO-7842 — buyer's matching purchase order;
- INV-2026-119 — seller's invoice referencing PO-7842;
- Delivery note or acceptance record — evidence of the supplied milestone, where relevant.
With Proposa proposal software for freelancers, you can keep the quote, recorded client decision, messages, and shared documents attached to one client link. If you also need to track proposal views and client responses, the same link records the activity around the quote. The buyer still issues and approves its PO; Proposa preserves the commercial record around it.
Sources and further reading
- UK Department for Work and Pensions: No Purchase Order, No Pay
- UK Department for Transport: purchase order conditions of contract
- Homes England: low-value purchase order contract conditions
From quote to clear approval
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