Purchase order vs invoice: who creates each, when it's sent, and how they work together in the buying process. Clear comparison plus free invoice templates.
Purchase Order vs Invoice: Who Sends What
A purchase order (PO) is created by the buyer to request goods or services — it says "I want to buy this." An invoice is created by the seller to request payment — it says "here's what you owe me." The PO comes first; the invoice follows delivery.
Comparison Table
| Aspect | Purchase Order | Invoice |
|---|---|---|
| Created by | Buyer | Seller |
| Sent | Before delivery | After delivery |
| Purpose | Authorise a purchase | Request payment |
| Contains | Items, quantities, agreed price | Items, price, tax, total, due date |
| Reference | PO number | Invoice number (often cites the PO) |
How They Work Together
- Buyer issues a PO to authorise the order
- Seller delivers the goods or services
- Seller sends an invoice that references the PO number
- Buyer matches invoice to PO and delivery, then pays
This "three-way match" (PO, delivery, invoice) is how finance teams prevent overpayment and fraud.
Get the Invoice Right
Always quote the client's PO number on your invoice — it speeds up approval. Build a compliant one from our free invoice templates and number it cleanly with the invoice number generator.
Frequently Asked Questions
Does every invoice need a purchase order?
No. POs are common in B2B and procurement-heavy businesses. Many freelancers and small sales invoice directly without one.
Can a purchase order be used as an invoice?
No — they serve opposite roles. The PO authorises the buy; only the seller's invoice legally requests payment and records revenue.
What is a PO number?
A unique reference the buyer assigns to a purchase order. Quoting it on your invoice links the two documents for faster approval.
2026 Invoice Compliance & Fast Settlement Checklist
Verify these core line items before dispatching your billing documentation:
Sequential & Distinct ID
Maintain structured, unbroken numbering (e.g. INV-2026-001) for clean tax audits.
Direct Payment Rails & Pay Now Button
Embed Stripe, ACH, or instant wire links directly on the PDF for 1-click settlement.
Itemized Tax & SAC/HSN Codes
Clearly isolate gross subtotal from applicable GST/VAT percentages and line deductions.
Explicit Due Dates & Late Terms
State exact calendar deadlines and recurring late-interest policies upfront.
Reviewed by Finance & Document Structuring Specialists
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