You finished a commercial job six weeks ago. Clean work, signed off, invoice out the next morning. Now you're on hold with the customer's accounts payable line, trying to find out why the check never showed.
The answer, once you finally reach a human: your invoice got kicked back on day two because it didn't carry a purchase order number. Nobody called to tell you. It sat in a rejection queue while your 45 days quietly ran out, and now the clock starts over.
Here's the part that should bother you. That whole mess was preventable with one question asked when the call came in. The PO number isn't paperwork you chase at the end of a job. It's something you capture at booking, before the truck ever rolls.
Why AP kicks it back, and why you hear about it late
Big commercial customers don't pay the way a homeowner does. The person who called you for service almost never cuts the check. Your invoice goes to accounts payable, usually just called AP, a separate department whose whole job is matching invoices to spending someone already approved.
That matching step is the catch. Before your work ever got the green light, someone on their side typically opened a purchase order, a PO, which is the internal document that authorizes the spend and gets its own number. AP will only pay an invoice that carries a matching PO number. No number, no match, no payment.
What makes it sting is the silence. A bounced invoice rarely comes back with a note explaining itself. It drops into a rejection queue or an exceptions folder and sits there. You assume you're inside the 30 or 45 day window. You're not even in line.
Catch the PO number when the phone rings
The fix is boring, which is exactly why it works. You ask for the PO number at the moment you book the job, the same way you already ask for the address and the gate code.
Most callers have it handy or can grab it in a minute. Some don't, and that's worth knowing right now instead of six weeks from now. Either way, you've turned a 45 day surprise into a checkbox.
Build these fields into your intake, wherever that intake already lives:
- The PO number itself, written exactly as they say it, letters and all
- The AP contact, a real name and email, not just "billing"
- The dollar limit on that PO, so you know before you blow past it on a bigger job
- Where the number goes, since some accounts want it in a specific spot on the invoice
- The billing address, which is often nowhere near the job site
None of that takes a new system. It's one more line on a form you already fill out, asked by whoever answers the phone.
The AP contact is worth as much as the number
A PO number gets your invoice in the door. A name gets it unstuck when something goes sideways later, and with commercial billing something usually does.
So while you've got the caller on the line, pin down three quick things:
- How they want invoices submitted (a vendor portal, a specific email, or mailed paper)
- Their payment terms in days, so you know the real clock you're on
- Whether a signed field ticket has to ride along with the invoice to get paid
Write the answers in the customer file, not on a job ticket that gets buried the day after the work's done. You set this up once per account and reuse it on every call after.
Flag the jobs still missing one before the truck rolls
Booking-time capture catches most of it. A short daily pass catches the rest, because a PO sometimes gets promised at booking and never actually arrives.
Before dispatch, run one quick check over tomorrow's commercial work:
- Pull tomorrow's schedule and filter down to the commercial accounts
- Check each one for a PO number already sitting in the file
- For any that's blank, call the AP or customer contact that same afternoon
- If it's still blank at dispatch, make a deliberate call: roll with written approval in hand, or hold the job
Residential stops skip all of this. The whole point is to spend thirty seconds flagging the handful of commercial jobs where a missing number means a missing check.
When there really isn't a PO yet
Sometimes the work is real and the PO just hasn't caught up to it. An emergency call on a Friday in August doesn't wait for a buyer to open a requisition. That happens, and you still go.
That's fine, as long as you don't pretend the gap isn't there. Get the approval in writing before anyone starts:
- An email from your contact approving the work and the rough amount
- The words "PO to follow" with a date they expect to have the number
- The name and title of whoever's actually signing off on the spend
Be straight with yourself about what that buys you. A promise isn't a PO, and AP doesn't pay promises. Treat written approval as a reason to start, then chase the real number within a day or two, while the person who approved it still remembers the call.
Worth doing this week
You don't need new software for any of this. Pick a couple and start:
- Add a PO number field to your commercial intake and mark it required
- Pull last quarter's slow-paying commercial invoices and count how many were missing a PO. That's your number, and it's usually bigger than you'd guess.
- Build the one-line check into your pre-dispatch routine, every day
- Save each commercial account's AP contact and submission method in the customer file, once
- Coach whoever answers the phone to ask for the PO number out loud on every commercial call
If wiring this into your scheduling and intake sounds like more than you want to own, that's the kind of quiet plumbing we set up at AI Agency Houston. Either way, the question costs you ten seconds at booking and saves you a 45 day chase at the end.