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E-Invoicing

This information only applies to self-hosted WHMCS installations. WHMCS Cloud does not currently support this module.

The E-Invoicing addon module exports the invoices that WHMCS publishes for your clients to a third-party e-invoicing service. That service generates an e-invoice that meets the relevant tax authority’s requirements, then exchanges the document with that authority. This helps you meet current and upcoming e-invoicing mandates without changing how you bill your clients in WHMCS.

The e-invoicing service generates each e-invoice in the Peppol BIS Billing 3.0 format (UBL/XML), the standard that many EU e-invoicing mandates require.

This addon module is in a limited release:

  • WHMCS does not include the addon module by default. WebPros will invite a small group of WHMCS users to the limited release by email, and only invited users can download the addon module.
  • The addon module supports installations in Belgium only. We strongly recommend that you configure it for use in Belgium only. If you configure it for another country, you may encounter errors.

Activation

You will need to purchase, download, and upload the addon module before you can activate it through the Admin Area.

To do this:

  1. Follow the link in your E-Invoicing invitation email to access the addon module listing.
  2. Click Enable e-invoicing to view a list of available plans.
  3. Choose a plan and click Buy Now.
  4. Enter your payment details and complete the purchase.
  5. Go to Services > My Products & Services.
  6. Select the E-Invoicing addon module and select the Downloads tab.
  7. Download the E-Invoicing addon module.
  8. Unzip the .zip file.
  9. Upload the einvoicing directory to the /modules/addons folder of your WHMCS installation.
  10. Go to Configuration () > System Settings > Addon Modules.
  11. Click Activate for E-Invoicing.
  12. Click Configure.
  13. Enter your license ID and license key.
    To find your license ID and license key, log in to WHMCS.com, go to Services > My Products & Services, and select the E-Invoicing addon module.
  14. Enter your company’s name, email address, and address.
  15. Select Belgium for Country.
  16. Select the admin role groups that will have access to this addon module.
  17. Click Save Changes.

How E-Invoicing Works

When WHMCS publishes an eligible invoice, the addon module automatically exports it to the e-invoicing service. The e-invoicing service then exchanges the e-invoice with the relevant tax authority, and returns status updates to WHMCS through a webhook.

To export an invoice, the addon module requires all of the following data:

RequirementEligible State
Invoice statusThe invoice can use any invoice status that is not Draft.
Invoice totalThe invoice’s total must be greater than zero. The addon module excludes zero-value invoices to meet EU compliance rules.
Invoice taxThe invoice must include a tax.
Client E-InvoicingYou have enabled E-Invoicing for the client.
Client dataThe client’s data is complete, and the addon module has exported the client’s contact successfully.
Export statusThe addon module has not already exported the invoice. It cannot re-export an invoice after it sends it.

To monitor each invoice’s progress, go to the Invoice Management section at Addons > E-Invoicing and review the E-Invoicing Status column. If an invoice displays Error, see E-Invoicing Invoice Export Errors.

If a client’s billing country changes to one that the addon module does not support, it automatically disables E-Invoicing for that client and records the change in the Activity Log at Configuration () > System Logs.

Credit Notes and Cancellations

When you cancel an invoice that the addon module already exported to the e-invoicing service, it automatically generates and sends a credit note to reverse that invoice in the external accounting and tax records. This keeps the e-invoicing service and the tax authority in sync with WHMCS.

If the addon module cannot send the credit note automatically, it records the error, and you can send the credit note manually. To do this, click Send Credit Note in the Invoice Management section at Addons > E-Invoicing. The maximum amount is the net amount that the addon module originally exported for the invoice.

The addon module also supports partial credit notes, which you can use when you need to reverse only part of an invoice.

Modifying an Invoice

After the addon module exports an invoice to the e-invoicing service, it treats that invoice as immutable, because legal compliance requires it. WHMCS cannot reduce the original invoiced amount, so if you need to correct an exported invoice, do not edit the original. Instead, cancel it and reissue a corrected invoice, which the addon module exports to the e-invoicing service as a separate document.

For more information, see Invoice Already Submitted Errors and Invoice Management.

Manage E-Invoices

To manage your e-invoices, go to the Invoice Management section at Addons > E-Invoicing. From here, you can:

  • Review each invoice’s status.
  • Retry an export that failed with an Error status.
  • Send a manual credit note for an exported invoice.

Logging

The addon module writes its activity to the Activity Log and the Module Log, which you can review at Configuration () > System Logs. For audit and debugging purposes, it also stores entries on your WHMCS instance in the mod_einvoicing_audit_log database table.

Troubleshooting

For more information on troubleshooting addon module issues, see Troubleshooting Addon Modules.

You may encounter the following common issues:

Error or IssueCauseMore Information
Saving the E-Invoicing addon module settings returns a validation error, or the addon module displays a configuration warning.This error occurs when a required value is empty or in an invalid format, or when you provide only one of the two license credentials.E-Invoicing Configuration Errors
The E-Invoicing addon module displays a License validation failed., Your license is suspended., or Validating license... license status.This issue occurs when the license credentials are incorrect, the E-Invoicing subscription has lapsed, or the server cannot reach the e-invoicing service.E-Invoicing License Errors
After you save valid settings, a banner displays The system failed to synchronize the account with the e-invoicing service.This error occurs when the license credentials are incorrect, the e-invoicing service is temporarily unavailable, or the server cannot reach it.E-Invoicing Account Sync Errors
An info icon appears next to a client in Client Management with the tooltip Client data is missing for e-invoicing. or The system failed to export the contact to the e-invoicing service., or the Activity Log includes a You have not enabled e-invoicing for the client. entry.This error occurs when required client information is missing or invalid, the e-invoicing service rejects the contact, or you have not enabled E-Invoicing for the client.E-Invoicing Client Data Errors
An invoice does not export, or it displays Error in the E-Invoicing Status column in the Invoice Management section at Addons > E-Invoicing.This error occurs when the invoice is not eligible for export, the system could not export the client contact, or the e-invoicing service returns an error.E-Invoicing Invoice Export Errors
Invoice details change after export, or you see the warning The system has already submitted this invoice for e-invoicing.This issue occurs because the system treats invoices as immutable after it exports them to the e-invoicing service, as legal compliance requires.Invoice Already Submitted Errors
An invoice exported successfully, but its e-invoicing status never updates, or webhook delivery fails with a 401 response.This issue occurs when the License Key is missing from the addon module settings or the webhook endpoint is not reachable from the e-invoicing service.E-Invoicing Status Update Errors
An invoice displays Refused in the E-Invoicing Status column in the Invoice Management section at Addons > E-Invoicing.This issue occurs when the recipient rejects the e-invoice through their own system.Refused E-Invoice Status
addon-modules invoices

Last modified: 2026 September 17