# Match supplier invoices to purchase orders with Gmail: n8n workflow

> Started by an arriving email, and works across Gmail and n8n data table. It hands the judgement calls to OpenAI.

Source: https://millionrounds.com/workflow/match-supplier-invoices-to-purchase-orders-with-gmail (Millionrounds; every figure on the page links to its filing or article)

[Automation library](https://millionrounds.com/workflows) · [Money admin](https://millionrounds.com/workflows?category=Money+admin#library)

# Match supplier invoices to purchase orders with Gmail

Started by an arriving email, and works across Gmail and n8n data table. It hands the judgement calls to OpenAI. 19 steps, 2 branches: a working afternoon to understand properly.

Medium Calls a model: OpenAI

[Download free](https://millionrounds.com/login?next=%2Fapp%2Fworkflow%2Fmatch-supplier-invoices-to-purchase-orders-with-gmail)

**19 steps** Medium: a working afternoon

**2** Branches: places the flow splits

**0** Loops or waits

**2** Services it connects to

## The flow

Starts it 1 Model 3 Logic 9 Service 6

The steps in the order they run, from what starts it.

- 1 **Watch The Invoice Label** Gmail trigger *Starts it*
- 2 **Model** Lm Chat Open Ai *Model*
- 3 **Settings** Set *Logic*
- 4 **Pull Out The Invoice Fields** Information Extractor *Model*
- 5 **Write The Query To The Supplier** Chain Llm *Model*
- 6 **Keep Only The PDFs** Code *Logic*
- 7 **Parse The Money** Code *Logic*
- 8 **Read The Query** Code *Logic*
- 9 **Is There An Invoice Attached?** If *Logic*
- 10 **Read The Open Purchase Orders** Data Table *Service*
- 11 **Everything In Hand** Merge *Logic*
- 12 **Log It As Held** Data Table *Service*
- 13 **Draft The Reply To The Supplier** Gmail *Service*
- 14 **Read The PDF** Extract From File *Service*
- 15 **No Invoice On This One** No Op *Logic*
- 16 **Read The Invoices You Have Seen** Data Table *Service*
- 17 **Match It Against A Purchase Order** Code *Logic*
- 18 **Is It Clear To Pay?** Switch *Logic*
- 19 **Log It As Cleared** Data Table *Service*

## How it's built

- **Starts on:** An arriving email
- **Steps:** 19, with 2 branches
- **Size:** Medium: a working afternoon
- **Connects to:** Gmail, n8n data table
- **Model:** OpenAI

## Questions

What does it need to run?

An n8n account, plus your own Gmail account, and a key for OpenAI. You connect your own accounts after importing it; none are included.

What starts it?

It starts on an arriving email.

Does it use AI?

Yes. It calls OpenAI. Model calls are billed by the provider, not by n8n.

How long does it take to set up?

Plan an afternoon. 19 steps is enough that you should read each one before running it.

How do I import it?

Copy the workflow, open a new workflow in n8n and paste. The steps appear on the canvas, ready for your own accounts.

**Before you run it**

Nothing here has been tested by us. It is somebody's working automation, read and described from its own steps. Treat the connections it wants as a list of accounts it will touch, and read the 19 steps before you point it at anything that matters.

## Run it in n8n

- **Create your n8n account** Free to start. n8n is where the workflow runs. [Create an n8n account ↗](https://millionrounds.com/n8n)
- **Download the workflow** Free with a Millionrounds account. [Download free](https://millionrounds.com/login?next=%2Fapp%2Fworkflow%2Fmatch-supplier-invoices-to-purchase-orders-with-gmail)
- **Paste it into n8n** Open a new workflow in n8n and paste. Then connect your own accounts.

Stored with the author's traces removed: canvas notes, instance identifiers, saved credential names and any live document they had left behind.

## Connects to

Each opens the other workflows that use it.

[Gmail](https://millionrounds.com/workflows?service=Gmail#library)[n8n data table](https://millionrounds.com/workflows?service=n8n+data+table#library)

## Workflows like it

Also money admin, with the same services where possible, closest in size first.

- [**Automate GST/VAT tax returns with OpenAI and Gmail** 19 steps · calls a model · Gmail](https://millionrounds.com/workflow/automate-gst-vat-tax-returns-with-openai-and-gmail)
- [**Intelligent invoice processing & notification agent** 19 steps · calls a model · Gmail, Slack](https://millionrounds.com/workflow/intelligent-invoice-processing-and-notification-agent)
- [**Process invoices and send weekly AI reports with OpenAI** 19 steps · calls a model · Gmail, n8n data table](https://millionrounds.com/workflow/process-invoices-and-send-weekly-ai-reports-with-openai)
- [**Automated event management with Typeform and Stripe** 19 steps · Gmail, Google Calendar](https://millionrounds.com/workflow/automated-event-management-with-typeform-and-stripe)
- [**Collect overdue payments with Slack** 19 steps · Gmail, Slack](https://millionrounds.com/workflow/collect-overdue-payments-with-slack)
- [**Approve employee expenses with OpenAI and Google Sheets** 18 steps · calls a model · Gmail, Google Sheets](https://millionrounds.com/workflow/approve-employee-expenses-with-openai-and-google-sheets)