E-invoicing via Peppol: what is mandatory?
Peppol is an international network that allows businesses to send invoices securely and in a standardized format from one accounting system to another. The goal: fewer administrative errors and less VAT fraud.
What does Peppol automatically handle?
Peppol uses a mandatory UBL format. If something technical is missing, your invoice will simply not be sent or accepted. This prevents common administrative mistakes such as missing invoice numbers, missing dates, incorrect customer details, or incorrectly formatted VAT numbers.
Peppol checks:
- Whether an invoice number and date are present
- Whether supplier and customer details are correctly structured
- Whether VAT rates and amounts are included
- Whether a valid total amount and recipient ID are provided
This significantly reduces accounting errors and processing issues.
What does Peppol not check?
This is where the risk lies. Peppol validates the structure of your invoice, not its content. An invoice can be technically correct and still cause problems during a VAT audit or a payment dispute..
Peppol does not verify whether:
- The applied VAT rate is correct for the transaction
- The customer is legally identified correctly (correct legal entity, registered office)
- The description of goods or services is sufficiently clear
- The delivery or service date is accurate
- Your payment terms are legally valid and clearly stated
- Your general terms and conditions are properly applied
A vague description, incorrect VAT rate, or missing payment condition will pass through Peppol without issue. The responsibility for a legally valid and substantively correct invoice lies entirely with you.
What must legally be included on an invoice in Belgium?
Belgian VAT legislation imposes strict invoicing requirements. The following information is mandatory on every invoice:
- Date of issue
- Sequential invoice number
- Name and address of your business
- VAT number of your business
- Name and address of the customer (B2B)
- VAT number of the customer (for intra-community transactions or B2B)
- Description of goods or services
- Delivery or service date
- Price excluding VAT, VAT rate, and total including VAT
- Any discounts
- Payment term (e.g. 14 days, 30 days…)
If any of this is missing, your invoice may be rejected by your customer, tax authorities, or even a court.
What should you also include (but is not mandatory)?
In addition to legal requirements, certain elements are strongly recommended, especially in case of late payment or legal proceedings.
General terms and conditions
Clearly state that your general terms and conditions apply.
For example:
"Our general terms and conditions apply to all our invoices and assignments. You can consult them at www.yourcompany.com/terms-and-conditions”
This helps you with:
- Recovery costs
- Interest charges
- Disputes
Consequences of late payment
Explicitly state what happens if an invoice is not paid on time.
For example:
- When interest starts (e.g. from the due date)
- A fixed compensation (e.g. 10% with a minimum of €40)
This significantly strengthens your position in debt collection.
Purchase order or reference number
For larger companies or public institutions, a purchase order (PO) is often required for internal processing.
Without a reference, invoices may be administratively blocked.
Contact details for questions or disputes
Provide a clear point of contact for invoice-related questions.
For example:
“For questions regarding this invoice: finance@yourcompany.com”
This prevents customers from justifying late payment with:
“We didn’t know who to contact.”
Your bank details (IBAN)
Clearly include:
- IBAN
- Account holder name
- (Optional) BIC
It may seem obvious, but this information is often missing or unclear.
What should you avoid including on your invoice?
Some elements can actually weaken your position in case of a dispute.
Vague descriptions
Avoid descriptions such as “services rendered”, “work as agreed”, or “various costs”. Instead, be specific:
“Installation of air conditioning system type X on 21/06/2025 at location Y.”
The more precise your invoice, the stronger your position in a dispute.
Informal or unnecessary notes
Avoid phrases like:
- “Sorry for the delay, sending this now”
- “We’ll arrange payment later”
These undermine your credibility in case of disputes.
Rounded amounts without detail
A total of €1,000 without explanation may raise questions.
Always provide a clear breakdown of:
- Hours
- Materials
- Services
Incorrect customer details
Always verify the correct VAT number, official name, and address of your customer. Errors can result in your invoice being declared invalid during an audit or dispute.
Checklist: what should be on an invoice?
Use this quick checklist when preparing your invoice:
✔ Invoice number
✔ Invoice date
✔ Supplier name and address
✔ Supplier VAT number
✔ Customer name and address
✔ Customer VAT number (B2B)
✔ Description of goods/services
✔ Delivery date
✔ Price excl. VAT
✔ VAT rate
✔ Total incl. VAT
✔ Payment term
✔ IBAN
✔ Reference to general terms and conditions
✔ Any interest or compensation clauses
Conclusion
A well-prepared invoice is both legally and commercially valuable. It avoids confusion, speeds up payments, and protects you in case of disputes.
Take five extra minutes to review your invoice before sending it, and use the tips above as a guideline.
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