Quickstart

Register your first invoice against the AEAT pre-production environment in under thirty lines. The flow is the same against production — only the environment flag and the certificate change.

Prerequisites

1. An AEAT-issued mTLS certificate in .pfx (PKCS#12) or PEM form. See Certificates for how to obtain it.
2. Bun 1.3.14 (or Node ≥ 20).
3. The SDK installed in your project (bun add verifactu-sdk).

Minimal client setup

import { VerifactuClient, Environment } from 'verifactu-sdk';
import { readFileSync } from 'node:fs';

const client = new VerifactuClient({
  environment: Environment.Preproduction,
  mode: 'verifactu',
  certificate: {
    pfx: readFileSync('./cert.pfx'),
    passphrase: process.env.CERT_PASS ?? '',
  },
  taxpayer: { nif: 'B12345678', legalName: 'My Company SL' },
  billingSystem: {
    producerName: 'My Company SL',
    nif: 'B12345678',
    systemId: 'JC',
    systemName: 'My App',
    version: '1.0.0',
    installationNumber: '0001',
    onlyVerifactu: 'S',
    multipleTaxpayer: 'N',
    hasMultipleTaxpayers: 'N',
  },
});

The client owns the hash chain, the flow controller (which respects the TiempoEsperaEnvio returned by the AEAT) and the per-call validator. You only need one instance per taxpayer.

Registering an invoice

const response = await client.registerInvoice({
  invoiceId: {
    issuerNif: 'B12345678',
    seriesNumber: 'A/2026/0001',
    issueDate: '2026-05-20',
  },
  invoiceType: 'F1',
  description: 'Consulting services — May 2026',
  recipients: [{ nif: '12345678Z', legalName: 'Customer SL' }],
  breakdown: [
    {
      tax: '01',
      regimeKey: '01',
      operationQualification: 'S1',
      taxRate: '21',
      taxBase: '100.00',
      taxAmount: '21.00',
    },
  ],
  totalTaxAmount: '21.00',
  totalAmount: '121.00',
});

console.log(response.csv);            // → AEAT CSV (Código Seguro de Verificación)
console.log(response.envelopeState);  // → 'Correcto' | 'ParcialmenteCorrecto' | 'Incorrecto'
console.log(response.records[0]?.state);

The response.records array carries one entry per submitted invoice with its per-record outcome (Correcto, AceptadoConErrores or Incorrecto) and any AEAT error code. See Error codes for the full catalog.

Rendering the mandatory QR

Every invoice issued under VERI*FACTU must carry a QR code linking back to the AEAT validation portal. The SDK renders it for you in PNG, SVG or DataURL form.

import { buildQrUrl, renderQrPng } from 'verifactu-sdk/qr';

const url = buildQrUrl({
  mode: 'verifactu',
  environment: 'production',
  invoice: {
    issuerNif: 'B12345678',
    seriesNumber: 'A/2026/0001',
    issueDate: '2026-05-20',
    totalAmount: '121.00',
  },
});

const png = await renderQrPng(url, { sizeMm: 35 });
// → Buffer ready to embed in your PDF/HTML invoice.

The QR size must be 30–40 mm per the AEAT specification. See the QR guide for the layout requirements.

Querying previously submitted invoices

In verifactu mode (only) the AEAT exposes a paginated query endpoint. The SDK returns an async iterable so you never have to manage cursors yourself.

for await (const page of client.queryInvoices({ year: '2026', period: '05' })) {
  for (const record of page.records) {
    console.log(record.invoiceId.seriesNumber, record.state);
  }
}

Cancelling

await client.cancelInvoice({
  cancelledInvoiceId: {
    issuerNif: 'B12345678',
    seriesNumber: 'A/2026/0001',
    issueDate: '2026-05-20',
  },
  generatedBy: 'E',
});

Where to go next

• Hash chain — how the SDK chains records and what the AEAT verifies.
• Validations — the 23 business rules enforced locally.
• Flow control — how the SDK respects TiempoEsperaEnvio and the 1 000-record-per-submission limit.
• Testing — running the e2e suite against AEAT pre-production.