Automation library · Money admin

Verify Japanese invoice registration numbers from Gmail

Started by an arriving email, and works across Gmail, Google Sheets and Slack. It hands the judgement calls to Gemini. 17 steps, 2 branches: a working afternoon to understand properly.

MediumCalls a model: Gemini

Download free
17 stepsMedium: a working afternoon
2Branches: places the flow splits
0Loops or waits
3Services it connects to

The flow

Starts it 1Model 3Logic 4Service 9

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

  1. 1Fetch Invoice EmailsGmail triggerStarts it
  2. 2Google Gemini Chat ModelLm Chat Google GeminiModel
  3. 3Invoice Fields ParserOutput Parser StructuredModel
  4. 4Extract Invoice PDF TextExtract From FileService
  5. 5Extract Invoice Fields with GeminiChain LlmModel
  6. 6Normalize Registration NumberCodeLogic
  7. 7Check Number FormatIfLogic
  8. 8Verify with NTA Invoice APIHttp RequestService
  9. 9Report Missing NumberSlackService
  10. 10Parse NTA ResponseCodeLogic
  11. 11Report NTA API FailureSlackService
  12. 12Log Verification ResultGoogle SheetsService
  13. 13Route by Verification ResultSwitchLogic
  14. 14Mark Invoice Email as ReadGmailService
  15. 15Alert Deregistered IssuerSlackService
  16. 16Alert Unregistered NumberSlackService
  17. 17Flag for Manual CheckSlackService

How it's built

Starts on
An arriving email
Steps
17, with 2 branches
Size
Medium: a working afternoon
Connects to
Gmail, Google Sheets, Slack
Model
Gemini

Questions

What does it need to run?

An n8n account, plus your own Gmail, Google Sheets and Slack accounts, and a key for Gemini. 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 Gemini. Model calls are billed by the provider, not by n8n.

How long does it take to set up?

Plan an afternoon. 17 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 17 steps before you point it at anything that matters.