Answer
Why does accounts payable keep rejecting my invoice?
AP rejects for a short, fixable list of reasons: a missing PO, the wrong legal entity, a missing tax ID, an unreadable format, or a duplicate. Here is each one, in the order it tends to happen, and how to stop the bounce-back.
When accounts payable keeps rejecting your invoice, it is almost never about the work; it is about the document failing a checklist. AP systems and clerks validate a fixed set of fields, and a single missing or mismatched one sends the whole invoice back. The good news is that the list is short and predictable. The faster path is to let the buyer supply the parts only they know, like the PO number and the exact billing entity, directly on the invoice, so it passes their checklist the first time instead of bouncing two or three times.
Why AP sends it back
Ranked by how often each triggers a rejection.
Most likely
There is no PO number, or the wrong one
Most mid-size and large buyers run purchase-order matching: the invoice has to quote a valid PO that matches an approved order, or AP cannot pay it. You often do not have the PO when you raise the invoice, and chasing it by email means reissuing a corrected document later.
JupiterInvoice lets the recipient add the PO number to the invoice themselves, after it is sent, without you reissuing and without the invoice number or payment clock resetting. See adding a PO number after sending.
Common
The invoice names the wrong legal entity
Large clients have many registered entities, and AP will reject an invoice billed to "Acme" when the contracting entity is "Acme Operations UK Ltd." You usually cannot know which entity is correct; the buyer can.
Rather than email edits back and forth, let the recipient correct the bill-to entity, address, and tax ID on the invoice directly, with every change versioned. See why your invoice has the wrong billing details.
Common
A required field is missing, often a tax ID
Depending on the country and the buyer, AP may require your tax or VAT number, their tax ID, a specific cost-centre reference, or a remittance address. A missing one is an automatic reject. Cross-border invoices add more required fields, and the rules differ by country.
Keep the fields the buyer needs on the invoice and let them fill in the references only they hold. For the country-specific requirements, see the relevant invoicing-by-country guide.
Less common
The format their system cannot ingest
Some AP systems scan or OCR incoming invoices, and a heavily designed PDF, an image, or an unusual layout can fail to parse. The invoice is "rejected" because their software could not read it, not because anything is wrong with the content.
A clean, hosted invoice page with a standard downloadable PDF is far easier for these systems to handle than a bespoke template or a photographed document. If the client uses a vendor portal, see when a client wants you to use their vendor portal.
Edge case
It looks like a duplicate
If you reissued the invoice to fix an earlier rejection and changed the invoice number, AP may now see two invoices for the same work and reject both pending clarification. Reissuing to fix small problems is itself a cause of rejections.
The way out is to not reissue for minor corrections at all. When the PO, entity, or a detail can be fixed on the original invoice in place, there is only ever one document and one number for AP to match against.
Two-minute diagnosis
- Ask AP for the exact reason. "Rejected" is not actionable; "no PO" or "wrong entity" is. They will usually tell you if asked directly.
- Get the PO and the correct bill-to entity from the buyer, not from your own records, which may be out of date.
- Fix it on the original invoice if you can, rather than reissuing a new number that risks a duplicate flag.
- Confirm the required fields for that client and country before resubmitting.
When AP keeps rejecting the invoice
Why won't they just tell me what is wrong?
Should I reissue the invoice with a new number?
The client added a PO after I sent it. Do I need to resend?
How do I know which fields a given client requires?
How does JupiterInvoice reduce rejections?
Last updated June 1, 2026
Send an invoice AP can actually clear
JupiterInvoice lets the recipient add the PO and correct the billing entity, address, and tax ID on the invoice itself, versioned, with no reissue. One invoice number, the right fields, fewer bounce-backs. Free, no signup.
Create your first invoiceNo signup required. Build now, save later.