Compliant e-invoicing, handled inside the billing system you already run.

If you are located or doing business in the EU, you probably know that every invoice you send in Belgium now has to satisfy a rule that did not exist two years ago.

Since January 1, 2026, B2B invoices between VAT-registered businesses must be exchanged as structured electronic documents across the Peppol network. A PDF attached to an email no longer counts.

For most WHMCS businesses that has meant one of two things: running a separate e-invoicing platform alongside WHMCS, or bridging the gap by hand. Neither is a good use of anyone's time.

We understand this and we've recently introduced the E-Invoicing addon module for WHMCS.

The module connects your WHMCS instance to a certified Peppol access point. When WHMCS publishes an eligible invoice, the module exports it automatically; the access point generates the Peppol BIS Billing 3.0 document, exchanges it with the relevant tax authority, and reports the outcome back into WHMCS. You do not need your own Peppol membership, a separate access point contract, or any working knowledge of UBL and XML.
Compliance deadlines are rarely convenient, and this one arrived with real teeth. Four things changed at once:

• Structured formats only. Invoices must be exchanged as Peppol BIS Billing 3.0 in UBL/XML. Traditional PDF invoices no longer satisfy the requirement.
• Certified transmission. Documents have to travel through a certified access point rather than ordinary email.
• The obligation attaches at issue. It applies when you issue the invoice, not when the customer pays it.
• Broad scope. Every VAT-registered business is covered for its B2B transactions.

The practical problem is not understanding the rule. It is meeting it without rebuilding a billing process that already works.
Automatic export on publication. When WHMCS publishes an eligible invoice, the module exports it with no manual step. It triggers on publication rather than on payment, which is what the Belgian mandate requires.

Peppol delivery through a certified access point. The access point generates the structured document, exchanges it with the tax authority, and returns status updates to WHMCS through a webhook. Nothing on your side needs its own Peppol registration.

Credit notes and cancellations. Exported invoices are immutable, as legal compliance requires. When you cancel an invoice the module has already exported, it generates and sends a credit note automatically to reverse it. Partial credit notes are supported, and you can send one manually if the automatic attempt does not go through.

Invoice management and retries. A dedicated Invoice Management screen at Addons > E-Invoicing shows the status of every invoice, lets you retry a failed export, and lets you issue a manual credit note. Activity is written to the Activity Log and the Module Log for audit and debugging.

The result is compliance that runs quietly in the background: no second platform to maintain, no duplicate data entry, and a clear record of what went out and what needs attention.
For billing administrators, e-invoicing becomes part of the billing run you already do. You choose which clients are enrolled, and from then on their invoices go out automatically.

For finance and compliance, every transmission is recorded with its status, and corrections follow the cancel-and-reissue path that auditors expect rather than an edit to an issued document.Step 1: Choose your plan. Select the invoice tier that matches your monthly volume and complete the purchase.

Step 2: Download the module. Go to Services > My Products & Services, select the E-Invoicing addon module, and download it from the Downloads tab.

Step 3: Upload it. Extract the archive and upload the einvoicing directory to /modules/addons in your WHMCS installation.

Step 4: Activate and configure. In your admin area, go to Configuration > System Settings > Addon Modules, activate E-Invoicing, then enter your license ID and key along with your company details.

Step 5: Enroll your clients. Enable e-invoicing for the clients who need it. Their future invoices are exported automatically.The module is built for WHMCS businesses that issue B2B invoices in Belgium. Before you start, few things are worth knowing:

• Belgium only at this stage. Support for other Peppol markets will follow.
• Self-hosted WHMCS 9.0 or later. WHMCS Cloud does not currently support the module.

Pricing is a monthly subscription based on the number of invoices you send, with tiers that scale as your volume grows.
Belgium's mandate is already in force, and the businesses handling it best are the ones that stopped treating compliance as a separate workflow. The E-Invoicing addon module brings Peppol e-invoicing into WHMCS so that a compliant invoice is simply the invoice you were going to send anyway.

If you invoice business customers in Belgium, this is the shortest route from where you are to compliant e-invoicing.

Get started today at https://www.whmcs.com/e-invoicing/.