Everything you need to know about the invoice

In this article, we will take a closer look at the how, what and why of the invoice.

What is an invoice?

An invoice is a document issued by a seller to a buyer. It lists the goods or services provided and the associated costs. The invoice serves as a request for payment.

‍What different types of invoices exist?

There are several types of invoices, including:

• Standard Invoice: for regular transactions.

• Credit note: an invoice that reflects a refund.

• Debit note: an invoice that requests additional payment.

When is an invoice required?

An invoice is mandatory when selling goods and services to companies or individuals in the EU. This applies especially to B2B (Business-to-Business) transactions and to cross-border deliveries within the EU. For private individuals, you do not normally need to issue an invoice unless a customer requests it or it is a sale where VAT (value added tax) is charged.

When should an invoice be sent?

An invoice must be sent no later than 15 days after delivery of the goods or services. 

How much time does a customer have to pay?

The payment term is often included in the terms and conditions of the invoice. Legally, the standard payment term in Belgium is 30 days after receipt of the invoice, unless otherwise agreed. For agreements between companies, this term can be extended to 60 days. Invoices addressed to private individuals must be paid within a "reasonable period". In practice, this usually means a payment period of one to two weeks.

What information is required on an invoice?

An invoice must contain at least the following information:

• Sequential Number: Each invoice must have a unique number. These numbers must be sequential, so invoice 123 must not be followed by invoice 125.

• Your information: Your company name, address, VAT number and bank account number.

• RPR address: If you have a corporation, list the appropriate court of commerce in your area.

• Customer details: Record your customer's company name, address and VAT number.

• Dates: Include both the date the invoice was issued and the date your offer was delivered.

• Descriptions: Provide a brief but specific description of each service or product.

• Quantities and unit prices: List the price per piece, metre, hour, etc., and quantity.

• Taxable amount: 

  • The total price excluding VAT. If you use multiple VAT rates, for example for different types of products, calculate the total price for each VAT rate.

  • List the VAT rates of all your services/products, the VAT amounts in absolute figures and the total of all VAT (in euros).

  • When invoicing to foreign countries, you usually mention "reverse charge VAT" to indicate that your customer must pay the VAT. Also, if you apply an exemption, state this on your invoice.

• Reference to previous invoices: If you issue multiple invoices for the same service, reference the previous invoices.

Banqup has its own tool for preparing invoices that ensures you don't forget anything! 

Not required, but recommended is to also include your terms and conditions and an interest for late payment. 

What is an electronic invoice or e-invoice?

An electronic invoice, or e-invoice, is an invoice sent and received in a structured electronic format. E-invoices must meet specific legal requirements to be considered a legal document and are mandatory for all as of Jan. 1, 2026. They offer benefits such as faster processing, lower costs and less chance of errors compared to paper invoices.

How do I determine the correct VAT rate?

VAT is a tax on consumption that is ultimately paid by the end user. This tax is collected at each step in the production and distribution process. The standard rate is 21%, but there are reduced rates of 0%, 6%, and 12% for specific categories of goods and services. Check with your accountant for more info. 

What happens if I make a mistake on an invoice?

If you make a mistake on an invoice, you should correct it by issuing a credit note (or debit note). A credit memo cancels all or part of the original invoice and contains the same information as the original invoice, but with the appropriate corrections. You then create a new, correct invoice. This keeps your records correct and prevents problems on tax returns.

How long should I keep an invoice? 

In Belgium, it is mandatory to keep invoices for 10 years. This obligation applies to both paper and electronic invoices and is intended for transparency and auditability in the event of a tax audit or legal disputes. It is perfectly legal to archive a scan or a copy of an original invoice as long as the origin and integrity of the invoice is guaranteed. Thanks to Banqup your invoices are kept in a legal archive. 

‍Can an invoice be time-barred?

The statute of limitations for an invoice varies depending on the type of invoice. For business invoices (B2B), the statute of limitations is usually 10 years. For payment obligations in a private context (B2C), the statute of limitations is usually 1 year. In some cases, however, the statute of limitations may be different; discuss this with your accountant.

What is Hermes?

Hermes is a solution offered by the Belgian government to ease the transition to electronic invoicing for companies. It enables companies to send electronic invoices to all their customers, regardless of the customer's preferred format. Hermes ensures that companies comply with the new e-invoicing mandates while remaining flexible and user-friendly. With the rise of mandatory e-invoicing, Hermes is expected to die out. 

‍What is Mercurius?

Mercurius is the Belgian government's central platform for sending and receiving electronic invoices (e-invoices) in transactions between companies and government agencies (B2G). You can best compare Mercurius to a post office where all government invoices arrive and from where they are further distributed to the various authorities (federal, regional, local) and government agencies.‍