Verify Tax IDs from PDF Uploads: n8n + Groq + Sheets + Gmail

Automatically verify tax IDs from uploaded PDF documents—then log, email, and return a JSON verdict

This n8n workflow accepts PDF uploads via a Lovable webhook, extracts the Tax ID using Groq, validates it against a Google Sheets “TaxID_Database,” emails the submitter through Gmail, records an audit trail in Sheets, and returns a final compliance verdict back to Lovable as JSON.

What this workflow does

• Receives uploads via Webhook: A POST webhook from Lovable sends a base64-encoded PDF plus submitter metadata.
• Deduplicates repeated submissions: It generates a request ID, normalizes incoming fields, and checks Google Sheets “Verification_Log” for a recent run with the same filename to return a cached duplicate result.
• Extracts Tax ID from the PDF: If not a duplicate, it extracts readable text from the PDF payload and sends it to Groq (OpenAI-compatible chat completions) to parse the Tax ID and document details as JSON.
• Handles missing Tax IDs: If Groq cannot extract a Tax ID, the workflow immediately returns a JSON error response to Lovable.
• Validates and matches: It normalizes the extracted Tax ID format, looks it up in Google Sheets “TaxID_Database”, and determines match score, entity mismatch, and a preliminary verification status.
• Produces a final verdict: The workflow sends verification facts back to Groq to generate a final compliance verdict with risk level, score, flags, summary, and recommended action.
• Audits, notifies, and responds: It appends the full verification audit record to Google Sheets, updates matched/unknown entries, emails the submitter via Gmail, and returns the final JSON result to Lovable.

Use cases

• SaaS onboarding that needs automated tax ID verification from PDF uploads.
• Risk screening workflows where mismatches must be logged and communicated to users.
• Operational audit trails for compliance teams using Google Sheets as a lightweight database.

Technical details

• n8n nodes: webhook, if, switch, code, gmail, and sticky note.
• LLM parsing: Groq (OpenAI-compatible chat completions) to extract Tax IDs and generate a compliance verdict.
• Data storage & lookup: Google Sheets tables “TaxID_Database” and “Verification_Log”.
• Return format: JSON verdict response back to Lovable.