{"product_id":"n8n-workflow-chase-unpaid-invoices-via-google-sheets-gmail-slack","title":"n8n Workflow: Chase Unpaid Invoices via Google Sheets + Gmail + Slack","description":"\u003ch3\u003eChase overdue invoices automatically—without pestering clients who already replied\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow runs every weekday morning to find unpaid, overdue invoices in \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e, checks \u003cstrong\u003eGmail\u003c\/strong\u003e for any recent client replies to hold those cases, then drafts and sends stage-appropriate reminder emails using \u003cstrong\u003eOpenAI\u003c\/strong\u003e and posts a single \u003cstrong\u003eSlack\u003c\/strong\u003e digest of what happened.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSchedules and holiday awareness:\u003c\/strong\u003e Executes on a weekday-morning schedule, loads configuration values, and checks \u003cstrong\u003edate.nager.at\u003c\/strong\u003e for public holidays to determine whether reminders should be sent today.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIdentifies eligible invoices:\u003c\/strong\u003e Reads the invoice ledger from \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e and prior chase history from an \u003cstrong\u003en8n Data Table\u003c\/strong\u003e, then selects invoices that are overdue and eligible based on due date, status, \u003cem\u003ehold_until\u003c\/em\u003e, chase limits, and minimum gap rules.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrevents duplicate chasing via Gmail:\u003c\/strong\u003e Searches \u003cstrong\u003eGmail\u003c\/strong\u003e for recent inbox messages and \u003cstrong\u003eholds\u003c\/strong\u003e any invoice where the client has replied within the configured window—capturing the email subject and snippet for review.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWrites context-aware reminders:\u003c\/strong\u003e Processes invoices one at a time and uses \u003cstrong\u003eOpenAI (GPT-5.6)\u003c\/strong\u003e to draft a nudge, firm reminder, or final notice. Tone is adjusted based on days overdue and payment history.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSafety validation:\u003c\/strong\u003e Validates and sanitizes the draft to ensure the correct invoice number and amount are included, falling back to a safe template if needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSends and logs:\u003c\/strong\u003e When \u003cem\u003edry_run\u003c\/em\u003e is disabled, sends the email via \u003cstrong\u003eGmail\u003c\/strong\u003e and upserts chase count and last-chased date into the \u003cstrong\u003en8n Data Table\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSlack digest reporting:\u003c\/strong\u003e Posts one consolidated \u003cstrong\u003eSlack\u003c\/strong\u003e summary of sent and held items (including reply snippets), plus totals.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eSaaS finance ops: reduce manual follow-ups while automatically pausing when clients respond.\u003c\/li\u003e\n  \u003cli\u003eFreelancers and agencies: send reminders at the right escalation stage without over-contacting.\u003c\/li\u003e\n  \u003cli\u003eAutomation engineers: maintain auditable chase history using an n8n Data Table and scheduled runs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eScheduling\/logic:\u003c\/strong\u003e if, set, code, no op nodes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations:\u003c\/strong\u003e Google Sheets, Gmail, Slack\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAI drafting:\u003c\/strong\u003e OpenAI (GPT-5.6)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHoliday check:\u003c\/strong\u003e date.nager.at\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChase tracking:\u003c\/strong\u003e n8n Data Table (upsert chase count + last-chased date)\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":45899946557619,"sku":"N8N-18719","price":30.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/Ku-4PMzDIKVilFXuCVHAd_VeNHqDT1.png?v=1787735061","url":"https:\/\/buyflowscripts.com\/products\/n8n-workflow-chase-unpaid-invoices-via-google-sheets-gmail-slack","provider":"N8N Commerce","version":"1.0","type":"link"}