The invoice that came back after six weeks
The agency invoices a large client for a campaign. Six weeks later, with no payment, the finance manager chases and learns the invoice was rejected by the client's accounts payable portal on day two because the PO number was missing. Nobody at the agency was told. The client's marketing contact raises a new PO, which needs sign-off from her manager, who is on leave.
On another account, the PO covered the first half of the year's retainer and has run out. The invoice goes in against the old PO and is rejected again. Cash that should have arrived months ago is sitting in a portal nobody at the agency checks.
Why purchase orders cause so much trouble
- The PO is sent to the account manager by the client contact, and it may not reach finance.
- One client can have several POs at once: one per campaign, one for the retainer, one for media.
- POs have values and end dates, and nothing tracks how much of each has been invoiced.
- Large clients use supplier portals such as Coupa or Ariba with their own rules, and rejections arrive as automated emails that go to a general inbox.
- Work often starts before the PO arrives because the client promised it was on its way.
The agency's invoicing is only as good as its PO records, and those records are usually an email in someone else's inbox.
The cost of rejected invoices
Payment is delayed, sometimes by months, while a fresh PO is raised or the invoice is resubmitted. Finance staff spend time chasing and resubmitting. Work done without a PO is at risk of never being paid if the client's budget closes. Account managers end up in awkward conversations with clients about paperwork instead of work.
The PO tracking we build
- Each client PO is recorded when it arrives, with number, value, currency, dates and the job, retainer or media it covers. POs forwarded to a dedicated address are read automatically.
- Jobs and retainers in your project tool or CRM are linked to their PO, and any client flagged as "PO required" cannot have work booked without one or without a named person accepting the risk.
- Invoices are drafted in Xero or QuickBooks with the correct PO number and any reference format the client's portal requires.
- The remaining value on each PO is tracked as invoices are raised, with a warning to the account manager when it is running low or near its end date, so a new PO can be requested early.
- Rejection emails from supplier portals are routed to finance and matched to the invoice, with the reason shown.
- A monthly list shows every client PO, what is left and what expires soon.
| Problem | What the tracking does |
|---|---|
| PO number missing from invoice | Added automatically from the linked job |
| PO used up | Warning before the next invoice, not after |
| PO expired | Flag ahead of the end date |
| Work started without PO | Blocked or accepted by a named person |
| Portal rejection unnoticed | Routed to finance and matched to the invoice |
Some supplier portals allow invoice submission through an API or a structured file. Where they do, we can submit directly. Where they do not, we prepare the invoice in the format the portal expects.
Invoicing corporate clients after
The account manager forwards a new PO and it is recorded against the campaign in seconds. When she books extra work, the system shows the PO will not cover it and she asks the client for a top-up before starting. At month end, invoices carry the right numbers and go into portals first time. Finance sees rejections the day they happen, with the reason, and fixes them the same week.
Is this happening to your invoices?
- Invoices to large clients are rejected for missing or wrong PO numbers.
- Rejections are found only when payment is chased.
- Nobody tracks how much of each PO has been used.
- Work often starts before the PO arrives.
- POs live in account managers' inboxes rather than with finance.