What is a purchase order (PO)?

A purchase order (PO) is a document a client issues to you before the work happens, authorizing the project and setting aside a budget for it. It typically carries a unique PO number, a description of what is being bought, the agreed amount, and an approval from someone with spending authority on the client’s side.

How a PO fits the billing flow

Think of a purchase order as the client’s mirror image of your estimate. You quote the work; they issue a PO that says “yes, we approve this spend, here’s our reference number.” Once that PO exists, your job is to deliver the work and then bill against it. The standard order looks like this:

1. You send a quote or estimate describing the work, hours, and price.
2. The client approves internally and issues a purchase order with a PO number and an authorized amount.
3. You do the work.
4. You send an invoice that references the client’s PO number so their accounts-payable team can match it and release payment.

Not every client uses POs. Solo clients and small businesses often skip them entirely and approve your estimate directly. But larger clients, agencies, universities, and government departments frequently require a PO number on every invoice before finance will pay you. When a client asks “what’s your PO process?” they usually mean: send a quote, we’ll issue a PO, then invoice us and quote that number back.

A real-world example

Say a marketing director hires you to redesign a landing page for $3,000. Her company’s policy is that any spend over $1,000 needs a PO. So she sends you PO number PO-4821 authorizing $3,000 of design work. You build the page, then issue your invoice for $3,000 with “Ref: PO-4821” clearly on it. Her accounts-payable team matches your invoice to the open PO, sees the amounts agree, and pays you. Without that number, your invoice might sit in a “needs more info” pile for weeks.

Tip: Always ask new corporate clients up front whether they need a PO before they can pay an invoice. Finding out after you have delivered the work is the most common cause of a slow first payment.

How Fee-Lion handles it

Fee-Lion does not have a separate PO module, and most freelancers do not need one. The PO is the client’s document to create, not yours. What you need is a clean way to reference their PO number so your invoice clears their finance team. You have two easy spots for it:

• A line item or note on the invoice. When you build an invoice, add the PO number in the invoice notes or as a clearly labeled line so it prints on the PDF the client downloads from the portal.
• Tags. Tag the invoice with the PO number if you want to filter and pull it up later in reports.

Because your estimate already mirrors a PO, the smoothest path is to quote the work as an estimate, let the client approve it in the no-login portal, and then convert that approved estimate straight into an invoice. Drop their PO number into the notes during conversion and you have a tidy paper trail: your estimate, their approval, your invoice, and the matching reference. If your client’s accounting or tax setup has specific PO requirements, check with their finance contact or your own accountant, since procurement rules vary by organization and location.

What’s next

• How to create an estimate
• How to convert an estimate
• Add line items and edit an invoice
• Tag invoices for reporting