How to Email Accounts Payable About an Unpaid Invoice

When you email accounts payable about an unpaid invoice, address the AP inbox directly, use the invoice number as the subject line, and state four things in the first two lines: the invoice number, the amount, the original send date, and what you need — payment status, a payment date, or remittance advice.

AP departments do not run on relationships. The person you sold to has no authority over when you get paid, and a friendly reminder to your usual contact often just sits in an inbox they don't check for finance requests. AP runs on matching documents: your invoice against their purchase order, their three-way match, their payment run calendar. An email that reads like a document lookup gets answered faster than one that reads like a favor.

The rest of this guide covers the exact wording for the first nudge, what to do when AP says the PO doesn't match or the vendor portal rejected your invoice, how to ask for remittance advice, and how to escalate when your invoice has gone quiet — including the case where the person who approved it no longer works there.

Before you start: what to have next to you#

Every template below assumes you have these on hand before you open the email. Missing even one of them is the single biggest reason AP asks a clarifying question instead of just paying.

• Invoice number — exact, as it appears on the invoice PDF
• PO number, if the client uses purchase orders (ask if you don't have one on file)
• Vendor ID or supplier number, if you've been assigned one in their system
• Amount due and currency
• Original invoice date and the date you first sent it
• Payment terms (Net 30, Net 60) so you can state whether it's actually overdue yet
• A copy of the invoice attached as a PDF, not just pasted as text

How do you write the first email to accounts payable?#

Send it to the AP department alias — usually [email protected], [email protected], or a name pulled from their invoice submission instructions — not to your day-to-day contact. Cc your contact so they know you're chasing it, but don't rely on them to relay it.

1. 1

   Send the first AP nudge

   Subject: Invoice [INVOICE NUMBER] — payment status check Hi [AP TEAM / NAME], I'm following up on invoice [INVOICE NUMBER] for [AMOUNT], sent on [ORIGINAL SEND DATE] under PO [PO NUMBER] (vendor ID [VENDOR ID], if assigned). Terms are [Net 30/60], which puts the due date at [DUE DATE]. Could you confirm the invoice was received and matched, and let me know the expected payment date? I've attached the invoice again in case it needs re-filing. Thanks, [YOUR NAME]

2. 2

   Fix a missing or mismatched PO number

   AP's three-way match compares your invoice, the PO, and the goods-receipt or approval on their side. If any one is missing, the invoice sits unpaid without anyone flagging it to you. If AP replies that they have no PO on file, don't just resend the invoice — ask your original contact to confirm the PO number and reissue a corrected invoice under it, then resend to AP with the PO number in the subject line: "Invoice [INVOICE NUMBER] — corrected to PO [PO NUMBER]." A PO-less invoice at a company that requires POs will not enter their payment run no matter how many times you ask.

3. 3

   Resubmit after a vendor portal rejection

   Subject: Resubmitted invoice [INVOICE NUMBER] — corrected [FIELD] Hi [AP TEAM], The portal rejected invoice [INVOICE NUMBER] for [REASON GIVEN, e.g. "PO line item mismatch"]. I've corrected [WHAT YOU CHANGED] and resubmitted through the portal as of [DATE]. Confirmation number is [PORTAL CONFIRMATION ID, if given]. Could you confirm it's now in queue for the next payment run? Let me know if anything else needs adjusting before it's re-rejected. Thanks, [YOUR NAME] Most portals reject silently on the vendor's own error log and never notify AP that a submission failed — so a portal rejection is often invisible to the person you'd normally chase. Emailing the fix, not just resubmitting through the portal, is what actually gets a human to look.

4. 4

   Ask for remittance advice

   Remittance advice is the payment notice a company sends alongside or after a bank transfer, listing which invoice(s) the payment covers, the amount, and the date. Without it, a payment can land in your account with no way to match it to an invoice — which matters when you have several invoices open with the same client. Subject: Remittance advice request — invoice [INVOICE NUMBER] Hi [AP TEAM], Could you send remittance advice for invoice [INVOICE NUMBER] once it's paid, or confirm the payment run date if it hasn't gone out yet? We'd like to match the deposit against the invoice on our end. Thanks, [YOUR NAME]

5. 5

   Ask about the payment run date

   Larger companies pay on a fixed schedule — weekly, biweekly, or monthly — not on demand. If your invoice is approved but not yet paid, the honest question isn't "why haven't you paid" but "when is the next run." Subject: Payment run date for invoice [INVOICE NUMBER] Hi [AP TEAM], Invoice [INVOICE NUMBER] shows as approved on our end as of [DATE]. Could you confirm which payment run it's scheduled for, and the expected date funds go out? Thanks, [YOUR NAME]

6. 6

   Escalate to the AP manager

   Escalate after one unanswered nudge and roughly three business days of silence, or after a second unanswered follow-up on a smaller invoice. Escalating too early on a first email reads as impatient; waiting two weeks on a large company reads as passive. Subject: Escalation — invoice [INVOICE NUMBER], unpaid past due date Hi [AP MANAGER NAME], I've emailed the AP team on [DATE(S)] about invoice [INVOICE NUMBER] ([AMOUNT], PO [PO NUMBER]), now [X] days past its [DUE DATE] due date, without a response. Could you help confirm its status or point me to who owns it? I've attached the invoice and prior correspondence for reference. Thanks, [YOUR NAME] Attaching the prior thread matters here — it proves you already tried the normal channel and shows exactly what's outstanding, which is what turns an escalation into a two-line reply instead of a request to start over.

How AP process differs by company size#

The right email changes depending on how the company actually processes invoices. Guessing wrong wastes a round trip.

What to do when accounts payable doesn't reply#

Two nudges and an escalation email cover most cases. The one AP situations doesn't: your invoice was approved by someone who has since left the company, and nobody currently on staff will claim it.

This happens more than it should, and it's the one AP scenario that emotion genuinely cannot fix — the new hire reading your email has no memory of the work and no stake in resolving it. What moves it is documents, not persistence.

1. 1

   Confirm the departure before you escalate

   If your last three emails to a named contact bounce or go unanswered, check LinkedIn or the company site for a same-title replacement before assuming abandonment. Emailing a departed employee's inbox for weeks is a common reason invoices go quiet — the message is never read, and nobody is forwarding it.

2. 2

   Go to the general AP inbox with the paper trail attached

   Address the AP alias directly and attach the full chain: the original invoice, the PO, and the approval email or Slack screenshot if you have one. State plainly that the approver has left and you need a new internal owner. AP cannot verify unfamiliar work from memory — a documented approval is what lets someone else sign off in the departed employee's place.

3. 3

   Ask procurement, not just AP, if the trail is thin

   If you have no clean approval record, procurement or the department that originally engaged you is more likely to recognize the engagement than AP, who only ever saw a document, not the work. A short note copying both — "I believe [DEPARTED CONTACT] approved this before leaving; could someone confirm so AP can process it?" — routes the question to whoever can actually answer it.

A faster way to chase invoices without babysitting the thread#

Every template above still works manually — the problem is doing it for every overdue invoice, every few days, across every client on their own schedule. That's the part that's easy to let slip once you have more than two or three invoices open at once.

AI Emaily's approval-first agent can track an invoice thread and draft the next nudge — the status check, the escalation, the remittance-advice ask — on the schedule you set, so it's ready to send rather than something you have to remember to write. You approve every draft before it goes out; nothing sends on its own. See how follow-up tracking works at aiemaily.com/use-cases/follow-ups. We build AI Emaily.