An invoice is a document issued by a seller to a buyer to record a transaction and request payment. It plays a crucial role in financial processes, as it not only documents the sale of goods or services but also contains essential information that forms the basis for accounting and tax reporting.
Important: If you sell to a business customer, you are legally required to issue an invoice. However, for private customers, there is no general obligation to provide an invoice unless they specifically request one. In most cases, a simple receipt suffices as proof of payment, provided it includes basic details such as the date, quantity, and price.
"}},{"componentType":"sectionTitle","title":"How to correctly issue an invoice: mandatory information"},{"componentType":"paragraph","richBody":{"value":"To be legally valid, an invoice must contain certain mandatory information. Although specific requirements vary by country, the following elements are generally required on an invoice:
Made a mistake? You cannot simply edit or delete an invoice. Instead, you must issue a credit note to correct the error.
"}},{"componentType":"sectionTitle","title":"Simplified invoicing with e-invoicing"},{"componentType":"paragraph","richBody":{"value":"E-invoicing refers to the electronic creation, transmission, and receipt of invoices via a secure network, replacing paper or email-based invoices. Businesses are switching to Peppol, and for good reason: since the beginning of 2026, structured electronic invoicing via this European network is mandatory for all VAT-registered businesses in Belgium. Peppol enables standardised digital invoicing across borders and ensures that invoices are automatically and accurately processed within the recipient’s invoicing system. By using Peppol, businesses can exchange invoices more efficiently, reduce administrative burdens, and minimise errors. Discover everything you need to know about the new regulations in this article.
Although e-invoicing digitises and automates the invoicing process (machine-to-machine exchange), the legal requirements for invoices remain unchanged. Even structured electronic invoices must include all mandatory details, as outlined above. A major advantage of e-invoicing is that modern invoicing software automatically populates many fields when generating an invoice. For instance, the software recognises key information, which users can simply confirm or correct. When entering a company name, the system automatically retrieves the company registration number (CBE/VIES), and vice versa. Each invoice is also assigned a unique invoice number, generated automatically per financial year. The tool calculates the total invoice amount, based on the net price, VAT rate, and quantity. All of this contributes to faster, error-free invoicing, fully compliant with legal requirements.
To ensure a smooth transition to e-invoicing, the right invoicing software is crucial. A smart and integrated system automates the invoicing process, helping businesses get paid faster and spend less time on manual processing. With the free standard version of ING Invoice Manager, you can effortlessly send and manage structured digital invoices, fully aligned with the new regulations. Plus, you’ll save time and effort by automatically sharing invoices and receipts with your accountant.
"}},{"componentType":"sectionTitle","title":"Invoicing and VAT"},{"componentType":"paragraph","richBody":{"value":"The standard VAT rate in Belgium is 21%, which applies to most invoices. However, different VAT rates apply to certain categories of goods and services:
Invoicing international business customers within the EU? If your transaction involves B2B sales within the EU, you must submit an intra-community VAT declaration. This applies, for example, to Belgian webshops selling to Dutch customers and vice versa.In these cases, VAT is reverse charged: the seller does not apply VAT on the invoice, but the customer in the destination country is responsible for VAT settlement according to their local regulations. However, you must clearly indicate the VAT “reverse charge” on your invoice using the following references:
Additionally, always verify your customer’s VAT number via the European Commission’s VIES application. If the client is not VAT-registered, you must apply Belgian VAT.
For private customers within the EU, Belgian VAT must always be charged, just as you would for a domestic sale. However, an exception applies if you exceed the EU distance selling threshold (link in FR), in which case you are required to register your business in the destination country and pay VAT there.
"}},{"componentType":"sectionTitle","title":"The legal payment term for an invoice"},{"componentType":"paragraph","richBody":{"value":"The payment deadline for invoices depends on the type of customer. For businesses and self-employed individuals, the standard payment term is 30 days from the invoice receipt date. You may agree on a different term, but it cannot exceed 60 days. For private customers the law requires payment "within a reasonable period", which is usually one to two weeks in practice. The payment term is typically specified in the general terms and conditions of the supplier.
"}},{"componentType":"sectionTitle","title":"Payment reminder vs. final notice"},{"componentType":"paragraph","richBody":{"value":"If a customer fails to pay on time, you must remind them of their obligation. This can be done via a payment reminder or a formal notice, but there is a clear difference between the two. A payment reminder is a gentle notification, usually the first message sent when the invoice due date has passed.
If the invoice remains unpaid after this reminder, you should send a formal notice ("mise en demeure" or "ingebrekestelling" in legal terms). This is an official and legally binding document that is more strict and enforceable. It sets a final payment deadline for the overdue invoice. A formal notice must include all invoice details (including the due date and previous payment reminders), a clear deadline for payment, and a statement that the customer may be liable for additional costs, such as debt collection fees and late payment interest.
With ING Invoice Manager, you always have a clear overview of all your invoicing activities via a personal dashboard. The dashboard organises overdue invoices into different timeframes (+3 days, +1 week, +2 weeks), allowing you to track and follow up on outstanding payments more efficiently.
"}},{"componentType":"sectionTitle","title":"Additional considerations for invoicing"},{"componentType":"paragraph","richBody":{"value":"1) Invoice language
An invoice must be issued in the official language of the region where your business is registered, regardless of the customer's preferred language. In Flanders, invoices must be in Dutch, while in Wallonia, they must be in French. For businesses registered in Brussels, either Dutch or French can be used, depending on the company’s registration.
This language requirement also applies to e-invoicing. Although Peppol uses Universal Business Language (UBL) for structured e-invoicing, UBL is not a spoken or written language but a standardised XML format that ensures invoices can be accurately processed by accounting and ERP systems.
2) Invoice timing
Issuing invoices on time is essential, both for maintaining a healthy cash flow and for complying with VAT regulations. Businesses typically issue invoices by the 15th of the month following the service or delivery. VAT law requires that invoices be issued no later than the 15th working day of the month after VAT becomes chargeable.
3) Invoice copies
A traditional paper invoice must always be issued in duplicate, with one copy for the customer and another for the seller’s records. With structured digital invoicing, invoices are stored automatically, but the legal obligation to retain copies remains in place.
4) Retention period
Invoices must be kept for ten years, starting from 1 January of the year following their issue date. In exceptional cases, a longer retention period may apply. This also applies to structured electronic invoices.
With ING Invoice Manager, you always have access to your invoices for as long as you use the tool. They are securely and neatly stored within your invoicing system. Although invoices are not archived upon deactivation, you will be informed clearly and in good time, ensuring you have ample opportunity to export your documents and store them correctly.
"}},{"componentType":"highlight","title":"Efficient, simple, and compliant invoicing?","richBody":{"value":"With an ING business account, you can activate ING Invoice Manager for free. This smart invoicing tool lets you send and receive electronic invoices with ease. The standard version is fully compliant with the new regulations, ensuring you meet the invoicing standards while saving valuable time.
Thanks to its seamless integration with your ING business account, you can get started right away - without extra hassle. And when it comes to hassle, say goodbye to lost receipts. ING Invoice Manager keeps all your invoices and receipts in one place, ready to be shared effortlessly with your accountant. Less paperwork, more focus on your business!
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