n8n Workflow: Validate Portuguese NIF & Draft Invoice-Receipt in InvoiceXpress

Validate Portuguese NIFs & generate a draft Invoice-Receipt in InvoiceXpress—automatically

This n8n workflow manually runs to validate Portuguese NIF tax IDs, confirm your configured VAT taxes in InvoiceXpress, and then create a draft invoice-receipt (fatura-recibo) via the InvoiceXpress API, returning the new document ID, totals, and any validation warnings.

What this workflow does

• Runs on demand (manual execution) using provided sample payment data.
• Normalizes payment fields—customer, NIF, items, amount, and VAT rate—into a consistent internal structure.
• Validates VAT and NIF: checks payment totals and VAT rates, verifies the Portuguese NIF check digit, and (based on your settings) falls back to “Consumidor final” when the NIF is missing or invalid.
• Verifies taxes in InvoiceXpress: calls the InvoiceXpress API to list available taxes and ensures each configured tax name exists with the expected percentage (from your taxas_iva mapping).
• Builds the InvoiceXpress payload using net unit prices, selected taxes, and optional series and tax-exemption reason.
• Creates a draft document and outputs the created document ID, total, and any validation warnings.

Use cases

• Pre-check payments before creating documents in InvoiceXpress to reduce tax/VAT mismatches.
• Automate invoice-receipt creation for Portuguese customers while enforcing NIF validity.
• Standardize VAT handling by confirming configured tax names and percentages directly against InvoiceXpress.

Technical details

• n8n nodes: Manual Trigger, Set, Code, Sticky Note, HTTP Request.
• Integration: InvoiceXpress API (HTTP Request steps).
• Authentication: Use an n8n HTTP Custom Auth credential that sends api_key as a query string (e.g., { "qs": { "api_key": "YOUR_API_KEY" } }).
• Configuration: Update invoicexpress_base_url (e.g., https://YOUR-ACCOUNT.app.invoicexpress.com).