What is Purchase Order (PO) -- Definition, Examples & Free Template?
A purchase order (PO) is a commercial document issued by a buyer to authorize a purchase before payment. Learn the difference between a PO and an invoice, when freelancers need them, and how to use them in your billing workflow.
What Is a Purchase Order?
A purchase order (PO) is a formal commercial document a buyer sends to a vendor or service provider to authorize and initiate a purchase. It documents the buyer's intent to purchase specific goods or services at agreed-upon prices — creating a legally binding commitment once the seller accepts it. Think of it this way: the PO is the buyer's side of the transaction. While the seller sends invoices to request payment, the buyer sends POs to authorize purchases in advance. For freelancers, receiving a PO from a client signals that the engagement has passed internal approval — which significantly reduces the risk of non-payment.
Purchase Order vs. Invoice — Key Differences
| | Purchase Order (PO) | Invoice | |---|---|---| | Who issues it | Buyer | Seller | | When it's issued | Before the transaction | After goods/services are delivered | | Purpose | Authorizes and commits to a purchase | Requests payment for goods/services delivered | | Legal effect | Creates buyer's obligation to pay | Confirms seller's right to payment | | Binding? | Yes — once seller accepts | Yes — after acceptance of goods/services | | Contains | What's being bought, quantities, agreed prices | What was delivered, what is owed, payment terms | | Matched by AP | Used by buyer's AP to match against invoice | Sent by seller to buyer's AP department | | Who references it | Seller uses PO # on their invoice | Buyer's AP reconciles it against PO |
Sample Purchase Order
PURCHASE ORDER TechCorp Inc — Procurement Department PO Number TCPO-2026-0193 PO Date March 10, 2026 Payment Terms Net-45 Delivery Date April 15, 2026 Issued By (Buyer): TechCorp Inc Accounts Payable Department 1 Infinite Loop, MS-AQ Cupertino, CA 95014 Issued To (Seller): Apex Consulting Group 840 Broadway, Suite 1200 New York, NY 10003 Description Qty Unit Price Total Q1 2026 Strategy Advisory — Monthly Retainer 1 $3,500.00 $3,500.00 Operations Audit — Phase 1 Report 1 $1,200.00 $1,200.00 Executive Workshop Facilitation 4 hrs $175.00 $700.00 Reimbursable Expenses (estimated) — — $200.00 Subtotal$5,600.00 Estimated Expenses$200.00 PO Total$5,800.00 Terms & Conditions 1. Seller shall reference PO TCPO-2026-0193 on all invoices submitted. 2. Payment terms: Net-45 from date of invoice receipt. 3. Reimbursable expenses must be documented with receipts. 4. This PO is valid through April 15, 2026. Authorized Signature: _____________________ Date: _____________________
When Do Freelancers Encounter Purchase Orders?
POs are most common in formal B2B environments — corporate clients, government agencies, nonprofits, and any buyer with a structured procurement process. You won't see POs from small businesses or direct consumers, but they're nearly universal in enterprise freelancing. Typical scenarios for freelancers: - A mid-size tech company hires you for a 3-month project; their procurement policy requires a PO before any contractor can be paid - A nonprofit receives a grant and uses grant funds to hire a consultant — a PO is issued to authorize spending against the grant budget - A government agency contracts freelance services; the PO is part of a formal federal/state procurement process
How POs Flow Through Your Invoicing Workflow
When you receive a PO from a client, here's how it fits into your billing workflow: 1. Receive the PO — before starting any work, you have written authorization and an agreed budget 2. Review and accept — confirm the scope and total amount; note any constraints (e.g., not to exceed $X) 3. Deliver the work — execute against the scope as defined in the PO 4. Send your invoice — always include the PO number in the invoice header so the client's AP team can match it 5. Wait for payment — with a PO in hand, payment is far more predictable than with a verbal agreement
POs vs. Contracts — What's the Difference?
A purchase order covers a specific transaction: what is being bought, at what price, with what terms. A contract (or freelance contract) establishes the broader legal relationship: scope of work, IP ownership, confidentiality, termination clauses, and more. In practice, many freelance engagements have both: - A master services agreement (MSA) or contract that governs the overall relationship - Individual POs that authorize and budget specific engagements under that umbrella
The Bottom Line
Purchase orders are a sign of a mature, professional client — and a protection for you as a freelancer. When a PO lands in your inbox, you have written evidence that the work is authorized and funded. Always reference the PO number on your invoice to ensure smooth, fast payment. (Track your AP matching process →) (See how this differs from a simple invoice →) (Know your balance due →) Key Takeaways: 1. A PO is the buyer's authorization to purchase — before delivery, before invoicing 2. Always reference the PO number on your invoice to ensure AP matching 3. Receiving a PO signals that the buyer's internal procurement has approved the engagement 4. For high-value or long-term freelance work, POs should accompany a broader contract 5. Eonebill makes it easy to reference PO numbers on every invoice you send Track purchase orders, send professional invoices, and get paid faster — Try Eonebill Free Ready to automate your invoicing workflow? Get started with Eonebill today and spend less time on admin and more time on client work. View Pricing → | Glossary Home → | Home →