Automate Timesheet to Invoice Conversion with OpenAI, Gmail & Google Workspace — n8n Workflow

High complexity⚡ Trigger40 nodes🏷️ Invoice Processingby DIGITAL BIZ TECH

Overview

This workflow converts emailed timesheets into structured invoice rows in Google Sheets and stores them in the correct Google Drive folder structure.

It:

Listens to Gmail for timesheet attachments
Runs OCR and AI parsing
Looks up Customer and PO data from a Google Sheet
Organizes files in Client → Employee → Year folders
Reuses an existing invoice sheet or creates a new one and writes the invoice row

Quick Implementation Steps

Import the workflow JSON into your n8n instance.
Set

Nodes used

Google SheetsHTTP RequestGoogle DriveCodeOpenAI

Workflow Preview

OCR extraction
Sends each attachment to the OCR API and returns plain
Build invoice dates
Calculates the invoice date and due date using the time
create new year folder
Create invoice sheet
Generates the sheet name, creates a new Google Sheet, u
Write invoice row
Initializes the row structure, maps customer and timesh
Decide reuse or create sheet
Checks the merged search results. If a matching sheet e
Email intake and loop
Listens to Gmail for unread timesheet emails, splits al
Timesheet to Invoice Automation
How it works
The workflow automates converting emailed timesheets in
1. Email intake
Pulls unread Gmail messages with timesheet att
Customer and PO lookup
Looks up the sender in the Customer POs sheet and pulls
AI timesheet parsing
OpenAI reads the timesheet text and extracts employee n
Client folder discovery
Search Client Invoices folder, finds or creates the cli
## File naming and search
searches Drive for existing sheets with the employee a
Create new
create new client name, employee and year named folder
Build file names and search
Generates start based and end based file names from emp
Create invoice sheet
Generates the sheet name, creates a new Google Sheet, u
Write invoice row
append invoice rows
For new sheets, creates the sheet, sets timezone, moves
⚡
G
Gmail Trigger
Split Binary Attachments
L
Loop: Process Each Attac…
Extract Timesheet Data (…
Get Customer Info From P…
S
Set Invoice Date & Due D…
G
Generate Sheet Name (Emp…
S
Set: Invoice Range
I
If: File Already Exists?
If: Invoice Range is 15…
S
Set: File Name from Star…
Merge: Combine Folder S…
Create New Sheet
Move Created Sheet to Fi…
Set: Row Data
Sheets: Append Row
Sheets: Final Append
Sheets: Create Sheet
Sheets: Append Row1
Extract Text from Attach…
Search: Client Invoices …
Search: Client Folder by…
Search: File By Start Da…
Search: File By End Date…
Drive: Move Sheet To Fin…
S
Set: Empty Row Structure
S
Set: Spreadsheet (ID & …
Append: Final Row to Exi…
C
Check if Year Folder Exi…
Create Client Name Folder
C
Check Client Name Folder
Search: Employee Name Fo…
C
Check Employee Name Folder
Create Employee Name Fol…
Search: Year Folder
Create Year Folder
Create Current Year Folder
S
Set Timesheet JSON Fields
HTTP Request(new sheet)
HTTP Request1(create she…
40 nodes46 edges

How it Works

  1. 1

    Trigger

    The workflow starts with a trigger trigger.

  2. 2

    Process

    Data flows through 40 nodes, connecting code, gmailtrigger, googledrive.

  3. 3

    Output

    The workflow completes its automation and delivers the result to the configured destination.

Node Details (40)

GO

Google Sheets

googleSheets

#1
HT

HTTP Request

httpRequest

#2
GO

Google Drive

googleDrive

#3
CO

Code

code

#4
OP

OpenAI

n8n-nodes-langchain.openAi

#5

How to Import This Workflow

  1. 1Click Download JSON button on the right to save the workflow file.
  2. 2Open your n8n instance. Go to Workflows → New → Import from file.
  3. 3Select the downloaded automate-timesheet-to-invoice-conversion-with-openai-gmail-google-workspace file and click Import.
  4. 4Set up credentials for each service node (API keys, OAuth, etc.).
  5. 5Click Test Workflow to verify everything works, then activate it.

Or paste directly in n8n → Import from JSON:

{ "name": "Automate Timesheet to Invoice Conversion with OpenAI, Gmail & Google Workspace", "nodes": [...], ...}

Integrations

codegmailtriggergoogledrivegooglesheetshttprequestifmergeopenaisetsplitinbatches

Get This Workflow

Download and import in one click

Download JSONView on n8n.io
Nodes40
Complexityhigh
Triggertrigger
CategoryInvoice Processing

Created by

DIGITAL BIZ TECH

DIGITAL BIZ TECH

@dbt

Tags

codegmailtriggergoogledrivegooglesheetshttprequestifmergeopenaisetsplitinbatches
⚡

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