contix-mcp

contix MCP server: Spanish invoicing with Veri*factu

Run your Spanish invoicing from Claude, ChatGPT, Cursor or any MCP client: customers, invoices with the Veri*factu hash chain and QR, payments, expenses, quotes, recurring invoices, Facturae/FACe for the public administration, Modelo 303/349/390 figures, and a workspace for your accountant (gestoría). Hosted by contix, nothing to install. Works in any language your assistant speaks; the contix panel itself is in Spanish, English and German. This repository holds the public metadata; the server code is not open source.

https://api.contix.es/api/v1/mcp

Streamable HTTP · OAuth 2.1 (dynamic client registration + PKCE) or API key (Authorization: Bearer cx_live_…, read-only or read/write) · needs a contix account (30-day trial). Irreversible steps, like finalizing an invoice into the Veri*factu chain, ask for explicit confirmation.

Setup for Claude, ChatGPT and Cursor: contix.es/mcp · API reference: contix.es/api · OpenAPI: https://api.contix.es/openapi.json

All 80 tools

Invoices

• create_invoice: Create draft invoice
• update_invoice: Update draft invoice
• get_invoice: Get invoice details · read-only
• list_invoices: List invoices · read-only
• finalize_invoice: Finalize invoice (irreversible) · asks for confirmation / irreversible
• clone_invoice: Clone invoice to draft
• rectify_invoice: Rectify invoice (Veri*factu)
• cancel_invoice: Cancel/annul invoice (irreversible) · asks for confirmation / irreversible
• resubmit_invoice_aeat: Correct and resend Veri*factu record (subsanación)
• delete_invoice: Delete draft invoice
• send_invoice: Send invoice by email
• mark_invoice_sent: Mark invoice as sent

Customers and payments

• list_customers: List customers · read-only
• get_customer: Get customer · read-only
• create_customer: Create customer
• update_customer: Update customer
• record_payment: Record a payment
• list_payments: List payments of an invoice · read-only
• get_account_statement: Customer account statement · read-only
• send_reminder: Send payment reminder
• list_reminders_sent: List reminders sent · read-only
• check_vat_number: Check an EU VAT number (VIES) · read-only

Quotes and recurring invoices

• list_quotes: List quotes · read-only
• create_quote: Create quote
• update_quote: Update quote
• send_quote: Send a quote by email
• mark_quote_sent: Mark quote as sent
• convert_quote_to_invoice: Convert quote to invoice
• list_recurring: List recurring profiles · read-only
• create_recurring: Create recurring profile
• update_recurring: Update recurring profile
• generate_recurring: Generate invoice from recurring profile

Expenses, suppliers and bank

• list_expenses: List expenses · read-only
• create_expense: Create expense
• update_expense: Edit expense
• delete_expense: Delete expense
• attach_expense_receipt: Attach receipt to expense
• list_suppliers: List suppliers · read-only
• list_bank_imports: List bank imports · read-only
• delete_bank_transactions: Delete bank movements
• list_bank_trash: Bank trash · read-only
• restore_bank_trash: Restore bank movements

Tax figures and public administration

• get_modelo: Get AEAT tax model (modelo) · read-only
• get_libros_registro: Libros registro (facturas expedidas / recibidas) · read-only
• check_period: Check a period before handing it over · read-only
• get_invoice_facturae: Get Facturae XML (B2G) · read-only
• submit_invoice_to_face: Submit invoice to FACe (B2G)
• get_face_status: Get FACe status (B2G) · read-only
• calculate_modelo_303: Sum the Spanish VAT return (Modelo 303) · read-only
• calculate_vat: Calculate VAT (IVA) and IRPF withholding · read-only
• get_obligation_dates: Veri*factu and e-invoicing deadlines (Spain) · read-only
• validate_iban: Validate an IBAN · read-only
• validate_spanish_tax_id: Calculate/validate a Spanish DNI, NIE or CIF check character · read-only

Settings

• get_invoice_series: Get invoice series/numbering · read-only
• set_invoice_series: Set invoice series/numbering
• get_quote_series: Get quote numbering · read-only
• set_quote_series: Set quote start number
• get_invoice_defaults: Get invoice defaults · read-only
• set_invoice_defaults: Set invoice defaults
• get_invoice_footer: Get invoice footer · read-only
• set_invoice_footer: Set invoice footer
• get_invoice_display: Get invoice display options · read-only
• set_invoice_display: Set invoice display options
• get_product_groups: Get product groups · read-only
• set_product_groups: Set product groups
• get_subscription_status: Get subscription/trial status · read-only

For accountants (gestorías) and their clients

• invite_gestoria: Invite your gestoría
• gestoria_listar_mandantes: List gestoría clients · read-only
• gestoria_invitar_mandante: Invite a gestoría client
• gestoria_abrir_mandante: Open a gestoría client
• gestoria_resumen_mandante: Gestoría client: figures for a period · read-only
• gestoria_facturas_mandante: Gestoría client: list invoices · read-only
• gestoria_gastos_mandante: Gestoría client: list expenses · read-only
• gestoria_revision_mandante: Gestoría client: what is missing · read-only
• gestoria_export: Export all gestoría clients · read-only
• gestoria_certificado_mandante: Compliance certificate for a gestoría client · read-only
• gestoria_comisiones: Gestoría earnings from contix · read-only
• gestoria_cierre_config: Quarter-close reminders: current settings · read-only
• gestoria_cierre_configurar: Quarter-close reminders: change settings
• gestoria_cierre_vista_previa: Quarter-close reminder: preview for one client · read-only

The MCP server, the REST API and the web panel run on the same engine. The live list is tools/list on the endpoint.

Free tools without an account

A second, smaller server with six read-only tools, no account and no auth:

https://api.contix.es/api/v1/mcp/herramientas

• validate_iban: IBAN check (country length, ISO 13616 check digits); for Spanish IBANs also the account check digits and the bank with its BIC from the Banco de España registry. A 20-digit Spanish account number is converted to its IBAN.
• check_vat_number: EU VAT number lookup in the European Commission's VIES registry.
• calculate_modelo_303: sums the boxes of the Spanish quarterly VAT return with the formulas of the official AEAT form.
• get_obligation_dates: Veri*factu and mandatory B2B e-invoicing dates from the published rules.
• calculate_vat: base, VAT (IVA), optional recargo de equivalencia and IRPF withholding from an amount, also backwards from a total. It applies the rates it is given and does not choose one.
• validate_spanish_tax_id: check character of a Spanish DNI, NIE or CIF; with 1 to 8 digits it computes the DNI letter.

Same tools as a REST API without key: https://api.contix.es/api/v1/herramientas (docs). In the browser: contix.es/herramientas.

Claude Code plugin

Both servers plus a short skill on when to use them, in one step:

/plugin install contix --marketplace martinschenk/contix-mcp

Configuration

{
  "mcpServers": {
    "contix": { "type": "http", "url": "https://api.contix.es/api/v1/mcp" },
    "contix-herramientas": { "type": "http", "url": "https://api.contix.es/api/v1/mcp/herramientas" }
  }
}

Clients without OAuth: add "headers": { "Authorization": "Bearer cx_live_YOUR_KEY" } to the contix entry; the key is created in the contix panel under Ajustes → API keys.

Registry

Both servers are in the Official MCP Registry as es.contix/contix and es.contix/herramientas (the server.json files here are copies).

Contact

martin@contix.es · Privacy · Terms

contix is software that issues invoices, not a tax advisory service. Results are what you enter, computed; what is correct for your case you decide with your gestoría.