Automated Invoice Payment Tracking with OCR, Cloud AI, Slack & Notion DB

# How it Works This workflow automates Invoice & Payment tracking (with Approvals) across Notion and Slack. - **Ingest** - You drop invoices/receipts (PDF/IMG/JSON) into the flow. - **Extract** - OCR + parsing pulls out key fields (invoice no, vendor, currency, totals, receipt paid amount/date). - **De-dup & Match** - We canonicalize vendor + invoice_no and search Notion: - Primary match: Invoice No (+ optional Currency / Vendor (Canon)). - Fallback: uses document Amount Total and dates. - **Decide the action** - **create_unpaid** - new invoice (no payment). - **create_paid** - new invoice fully paid (unverified). - **create_partial** - new invoice with a first partial payment. - **update_partial** - add a partial to an existing invoice. - **update_mark_paid** - mark existing invoice paid in full. - **manual_review** - currency mismatch / overpayment / ambiguous. - **archive** - push to archive logs (from manual review). - **Slack approvals (one-click)** - A message shows previous paid, this receipt, new total, and Approve buttons (links to a Wait for Webhook resumeUrl). Reviewer picks: Approve Partial / Mark Paid / Manual Review / Archive. - **Notion updates** - We only write editable fields: Paid Amount (number), Status (select), Last Payment Date (date). - Formulas (e.g., Amount Total, Amount Due) recompute automatically. - Receipts are saved in a Receipts DB and related back to the invoice. - **Notifications & duplicates** - If duplicates are detected, Slack posts a simple list with clickable invoice names. - **Archiving** - From Manual Review, Archive goes straight to Archived Invoice DB (and optional Archived Source File DB) as a log entry - no pre-checks needed. # Set up Steps Prerequisites 1. Notion DB 2. 4 Slack Channels (**Invoice Input**, **Notification**, **Manual Review**, **Duplicate Alert (Optional)**) 3. AI Model (We use **Claude 3.5 Haiku**, Feel free to use the Latest Model) 4. OCR Parsing (We Used **ocr.space**, Feel Free to Change into any OCR Parsing you have) - **Create Notion DBs:** - **Invoice DB**: Title `Invoice No`; Number `Paid Amount` (editable); Select `Status`; Dates (`Issue/Due/Last Payment Date`); Formulas: - `Amount Total = round(Subtotal - Discount Amount + Tax Total, 2)` - `Amount Due = max(0, round(Amount Total - Paid Amount, 2))` - **Receipts DB**: `Invoice No`, `Vendor`, `Paid Amount` (number), `Currency` (select), `Paid Date` (date), `Receipt No`, `Source URL`; Relation to Invoice. - **Archived Invoice DB**: `Invoice No`, `Vendor`, `Reason`, `Source URL`, `Original Page ID`, `Archived At` (date). - *(Optional)* Source File / Archived Source File DBs. - Share all DBs with your Notion integration (*Add connections*). - **Add credentials in n8n:** Notion (integration token) and Slack (bot token). Invite the bot to your channel. - **Import the workflow/template:** Set each Notion node's **Database ID** and each Slack node's **Channel/Credential**. - **Map updates:** In the Invoice **Update Page** node, map **Paid Amount**, **Status**, **Last Payment Date**. In **Create Receipt**, map `Invoice` relation + receipt fields. - **Test:** Run with a sample invoice/receipt → click a Slack button → verify Invoice/Receipt updates in Notion → try Archive from Manual Review.