VeriFactu on Magento.
Every paid order, an invoice registered with the AEAT.

<?php
// app/code/YourCompany/Cofactu/Observer/InvoicePay.php
namespace YourCompany\Cofactu\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\HTTP\Client\Curl;

class InvoicePay implements ObserverInterface
{
    public function __construct(private Curl $curl) {}

    public function execute(Observer $observer): void
    {
        $order = $observer->getEvent()->getInvoice()->getOrder();
        $lines = [];
        foreach ($order->getAllVisibleItems() as $item) {
            $lines[] = [
                'descripcion'    => $item->getName(),
                'cantidad'       => (float) $item->getQtyOrdered(),
                'precioUnitario' => (float) $item->getPrice(),      // excluding VAT
                'tipoIva'        => (float) $item->getTaxPercent(),
            ];
        }
        $this->curl->addHeader('Authorization', 'Bearer ' . getenv('COFACTU_API_KEY'));
        $this->curl->addHeader('Content-Type', 'application/json');
        $this->curl->post('https://api.cofactu.com/api/webhooks/ecommerce-orders', json_encode([
            'platform'        => 'magento',
            'externalOrderId' => $order->getIncrementId(),
            'client'          => $order->getCustomerTaxvat()
                ? ['nif' => $order->getCustomerTaxvat(), 'nombre' => $order->getCustomerName(), 'email' => $order->getCustomerEmail()]
                : null,                                                // simplified F2 invoice
            'lines'           => $lines,
        ]));
    }
}