Belgium Freelancer Invoice Requirements: Complete 2026 Guide

Every freelance invoice you issue in Belgium must comply with a specific set of legal requirements under the Belgian VAT Code (BTW-Wetboek). These aren't suggestions. Getting them wrong can trigger rejected VAT deductions for your clients, penalties from the tax authorities, or both.

The mandatory elements include a sequential invoice number, the issue date, the full names and addresses of both seller and buyer, the BTW-nummer (Belgium's VAT identification number) for both parties, a clear description of the goods or services provided, the quantity and unit price, the applicable VAT rate and amount, and the total including VAT. Since January 2026, there is one more obligation: all domestic B2B invoices must be issued as structured electronic invoices sent through the Peppol network, not just PDFs or paper.

If you're reading this in English, you're far from alone. According to Belgium's National Institute for Social Security of the Self-Employed (INASTI), 165,826 of the country's nearly 1.3 million self-employed workers in Belgium do not hold Belgian nationality — roughly 13% of the total. In the Brussels-Capital Region, that share rises to 41.9%. Yet most official guidance on Belgian invoicing rules exists only in Dutch or French, scattered across government portals and accountancy blogs.

This guide consolidates the full compliance picture into a single English-language reference. It covers VAT registration and the BTW-nummer you need before issuing your first invoice, the small business exemption that lets qualifying freelancers operate without charging VAT, every mandatory field your invoice must contain, the 2026 Peppol e-invoicing mandate and what it means in practice, language rules that vary by region, and the requirements around credit notes, payment terms, and record retention.

VAT Registration: The BTW-Nummer Every Freelancer Needs

Before you issue your first invoice as a freelancer in Belgium, you need a VAT number. There are no exceptions and no grace periods. Operating without one means your invoices are legally invalid, and you risk fines from the tax authority.

The Belgian VAT number is called the BTW-nummer in Dutch (Belasting over de Toegevoegde Waarde) or the numéro de TVA in French (Taxe sur la Valeur Ajoutée). Both terms refer to the same tax, governed by the same federal legislation. Whether you work from Antwerp or Liège, the legal framework is identical.

The Registration Path: Enterprise Number First, Then VAT Activation

Registration is a two-step process:

Obtain an enterprise number. You register with the Kruispuntbank van Ondernemingen (KBO), known in French as the Banque-Carrefour des Entreprises (BCE). This is Belgium's central business register. You typically complete this step through an approved enterprise counter (ondernemingsloket), which handles the paperwork and verifies your qualifications.
Activate your VAT identification. Once you hold an enterprise number, you apply to the SPF Finances (Federal Public Service Finance) to activate it as a VAT number. The SPF Finances assigns your VAT identification, which follows a fixed format: the country code BE followed by 10 digits, such as BE 0123.456.789.

Your enterprise number and VAT number share the same digit sequence. The difference is activation status: until the SPF Finances formally activates it for VAT purposes, your enterprise number cannot be used on invoices as a VAT identifier.

Dutch vs. French Terminology: A Quick Reference

If you are an English-speaking expat navigating Belgian administration for the first time, the bilingual terminology can be disorienting. Here is what you will encounter:

English	Dutch (Flemish)	French
VAT	BTW	TVA
Enterprise number	Ondernemingsnummer	Numéro d'entreprise
Business register	KBO	BCE
Tax authority	FOD Financiën	SPF Finances
Self-employed worker	Zelfstandige	Indépendant

Government correspondence and official portals may use either language depending on your registered office location, but the underlying rules do not change.

Your BTW-Nummer on Every Invoice

Once registered, your BTW-nummer must appear on every invoice you issue. This is not optional formatting; it is a legal requirement under Belgian VAT law. You must also include the buyer's VAT number when the buyer holds one, which is standard practice for B2B transactions within Belgium and across the EU.

Omitting either number from an invoice can trigger rejection by the buyer's accounting department and may result in penalties during a VAT audit by the SPF Finances. Get in the habit of treating the BTW-nummer as mandatory invoice data from day one.

The Small Business Exemption (Kleine Onderneming)

Belgian freelancers whose annual turnover stays below EUR 25,000 (excluding VAT) can apply for the Kleine Onderneming (Dutch) or Petite Entreprise (French) exemption regime. This is Belgium's small business VAT exemption, and it fundamentally changes how your invoices work.

Under this regime, you do not charge VAT on your invoices. Every amount you bill is a net amount only. In return, you cannot deduct input VAT on your own business purchases. There is no quarterly VAT return to file in the traditional sense, though you must still submit an annual client listing to the SPF Finances.

The mandatory invoice statement. Every invoice you issue under the exemption must carry a specific legal mention. In Dutch, the required wording is:

Vrijgesteld van BTW — artikel 56bis WBTW

The French equivalent is:

Exempté de la TVA — article 56bis CTVA

This is not optional advisory text. Omitting it makes your invoice non-compliant. If you invoice in both languages or in English, include at least the version matching the language rules for your region.

If your annual turnover exceeds EUR 25,000, you must leave the exemption regime and transition to the standard VAT system. From that point forward, you charge BTW on all subsequent invoices at the applicable rate. You are also required to notify the SPF Finances of the transition within the prescribed timeframe. The shift is not retroactive to earlier invoices in that calendar year, but you must act promptly once the threshold is breached.

The exemption is voluntary. Qualifying does not mean you must use it. Freelancers below EUR 25,000 in turnover can opt into the standard VAT regime instead. This makes sense when your business expenses are significant — purchasing equipment, software subscriptions, or coworking space — because the standard regime lets you recover input VAT on those costs. If your expenses are minimal, the simplified invoicing and reduced administration of the Kleine Onderneming regime is usually the more practical choice.

Every Field Your Belgian Freelance Invoice Must Include

Belgian law sets out a precise list of fields that every VAT invoice must contain. These requirements come from Article 5 of Royal Decree No. 1 implementing the Belgian VAT Code, and missing even one field can result in rejected VAT deductions for your client or penalties during a tax audit.

Use this as a checklist against your own invoice template:

A sequential invoice number — each invoice must carry a unique number in an unbroken chronological series, with no gaps and no reused numbers
The invoice issue date
Your full name (or business name) and address as the seller
Your VAT number (BTW-nummer)
The buyer's full name (or business name) and address
The buyer's VAT number, if the buyer is VAT-registered
A clear description of the goods delivered or services performed — vague entries like "consulting" without further detail are insufficient
The quantity (or scope) and unit price of each line item
The date of delivery or completion of the service, if it differs from the invoice date
The applicable VAT rate(s) for each line item (e.g., 21%, 6%)
The VAT amount per rate, broken out separately when multiple rates apply
The total amount excluding VAT
The total amount including VAT
Any applicable exemption reference — for example, the mandatory Kleine Onderneming wording if you operate under the small business exemption, or an intra-Community supply reference where relevant

SPF Finances (the Belgian tax authority) uses your invoice number sequence as a primary audit tool. A gap between invoice 2024-047 and 2024-049 immediately raises a red flag, because it suggests a missing or unreported transaction. Most freelancers adopt a format like YYYY-001, YYYY-002 and reset at the start of each fiscal year, though any consistent chronological system is acceptable as long as no numbers are skipped or duplicated.

For invoices to other EU member states (intra-Community supplies of goods or services), additional requirements apply. Both your BTW-nummer and the buyer's VAT identification number must appear on the invoice. Where the reverse charge mechanism applies, you must include an explicit reference — typically the phrase "Reverse charge — Article 196 of Directive 2006/112/EC" or the equivalent — instead of charging Belgian VAT. Omitting this reference shifts the VAT liability back to you as the supplier.

Peppol E-Invoicing: What the 2026 Mandate Means for Freelancers

Since January 1, 2026, all domestic B2B invoices in Belgium must be issued as structured electronic invoices transmitted through the Peppol network using the Peppol BIS 3.0 standard. This is the single largest change to Belgian invoicing rules in recent years, and it directly affects every freelancer who bills Belgian businesses.

A PDF attached to an email no longer qualifies as a valid invoice for domestic B2B transactions. Structured e-invoicing means your invoice data is generated, sent, and received in a machine-readable XML format through certified Peppol access points. The distinction matters: a PDF is a visual document a human reads, while a Peppol e-invoice is a data file that accounting systems process automatically.

The scope is specific. The mandate applies to invoices exchanged between two Belgian VAT-registered businesses. If both you (the freelancer) and your client hold a Belgian BTW-nummer, the invoice must go through Peppol. Three categories remain outside the current mandate:

Cross-border invoices to clients in other EU member states or outside the EU
B2C invoices to private consumers
Invoices involving at least one non-Belgian party

For those transactions, you can continue using PDF invoices or other traditional formats.

Penalties are now enforceable. The Belgian tax authorities granted a tolerance period from January through March 2026 to allow businesses time to adapt. That grace period has ended. Fines for non-compliance start at EUR 1,500 for a first offense, and repeated violations carry progressively steeper penalties. The tax administration treats the absence of a valid structured e-invoice the same way it treats a missing invoice: you lose the right to deduct input VAT, and your client cannot claim their deduction either.

In practical terms, you need access to a Peppol-compatible invoicing tool or access point. Most cloud accounting platforms used in Belgium now support Peppol transmission, but you should confirm with your provider before your next billing cycle. If you still invoice manually or via email, you will need to adopt Peppol-compatible software for your domestic Belgian clients.

One related compliance detail worth addressing alongside e-invoicing is the structured payment reference. Belgian businesses commonly use Belgium's OGM-VCS structured payment reference format on their invoices to enable automated payment matching through the Belgian banking system. Including an OGM-VCS reference on your Peppol e-invoices helps your clients' accounting systems reconcile payments automatically, reducing follow-up on both sides.

Which Language Your Invoices Must Use

Belgium's language legislation (Taalwet in bestuurszaken) imposes a requirement that catches many expats off guard: the language on your invoice is not your choice. It is determined by the official language of the region where your registered office (maatschappelijke zetel) is located. Issuing an invoice in the wrong language can render it legally invalid, so this is a compliance point you cannot afford to overlook.

The regional breakdown is straightforward:

Flanders — invoices must be issued in Dutch
Wallonia — invoices must be issued in French
Ostbelgien (German-speaking Community) — invoices must be issued in German
Brussels-Capital Region — invoices may be issued in Dutch or French, as it is officially bilingual

If you are an English-speaking freelancer registered in Antwerp, your invoices must be in Dutch. If your registered office is in Liège, they must be in French. Your personal language preferences or the language you use with your client do not change this obligation.

You can add a translation, and many expat freelancers do produce bilingual invoices with an English column alongside the legally required language. This is perfectly acceptable, but understand that the version in the region's official language is the legally binding text. If there is any discrepancy between the two versions, the Dutch, French, or German text prevails. For a deeper breakdown of the specific rules and edge cases, see our guide to Belgian invoice language rules by region.

One important exception applies to cross-border invoicing. When you invoice a client established outside Belgium, these regional language rules do not apply. The language obligation stems from Belgian administrative law governing domestic documents, not from international commercial regulations. For cross-border invoices, you and your client are free to agree on any language — English included.

Credit Notes, Payment Terms, and Record Retention

Once your invoice is sent, three compliance areas govern what happens next: how you correct errors, when you can demand payment, and how long every document must stay on file.

Issuing Credit Notes

Belgian tax law does not allow you to delete or modify an invoice after it has been issued. If you need to correct an error — a wrong amount, a cancelled service, or returned goods — you must issue a credit note (creditnota in Dutch, note de crédit in French). This requirement exists to preserve the sequential numbering that Belgian VAT auditors rely on when reviewing your records.

A valid credit note must:

Reference the original invoice number it corrects
Include all the same mandatory fields as a standard invoice (your BTW-nummer, client details, date, description of the correction)
Clearly state the amount being credited and the applicable VAT adjustment

You then account for the credit note in your VAT return for the period in which it was issued, reducing your reported turnover and output VAT accordingly.

Payment Terms Under Belgian Law

Belgium transposed the EU Late Payment Directive into domestic legislation through the Wet Bestrijding Betalingsachterstand (Loi concernant la lutte contre le retard de paiement), and the rules it sets are mandatory.

The default payment term is 30 days from the invoice date. While you and your client can agree on a different period, the maximum contractual payment term is 60 days. Any contract clause that sets a longer deadline is unenforceable under Belgian law — the 60-day cap applies regardless of what the contract says.

A critical detail many freelancers miss: late payment interest accrues automatically by law, without you needing to send a formal reminder or demand letter. Once the payment term expires, the Belgian statutory interest rate applies from the next day. You do not need to invoke this right explicitly — it exists by operation of law. Stating your payment terms clearly on each invoice, however, helps avoid disputes and strengthens your position if collection becomes necessary.

Record Retention Requirements

Belgian law imposes two overlapping retention periods that every freelancer should understand:

Requirement	Duration	Legal Basis
VAT/tax invoice retention	7 years	BTW-wetboek (VAT Code)
Accounting records retention	10 years	Wetboek van Economisch Recht (Code of Economic Law)

The practical rule: keep all financial documents for 10 years from the end of the relevant tax year, satisfying both requirements.

Since the Peppol e-invoicing mandate took effect for B2B transactions, the same retention rules apply to structured electronic invoices. The key requirement is that your digital invoices must remain accessible and readable in their original format for the full retention period. Storing a PDF printout alone is not sufficient if the original was a structured Peppol file — you must retain the UBL data itself. Cloud-based accounting software that archives the structured format automatically is the most reliable way to meet this obligation without manual effort.

The 30% Expat Tax Regime and Freelancer Invoicing

Belgium offers qualifying international workers a significant tax benefit known as the 30% cost allowance regime (also called the BBIB/RIZIV special tax status). Under this regime, up to 30% of a qualifying worker's gross remuneration can be treated as tax-free expense reimbursement, representing costs inherent to working abroad. The recurring cost allowance is capped at EUR 90,000 per year. Originally governed by a 1983 circular, the regime was formally codified in Belgian tax law effective January 1, 2022, bringing clearer eligibility criteria and tighter compliance requirements.

The regime targets internationally recruited workers — both employees and self-employed professionals — who were not Belgian tax residents during the five years immediately preceding their arrival. To qualify, a freelancer must generally earn a minimum gross remuneration of EUR 75,000 per year before the cost allowance is applied. The worker must also have been recruited from abroad or transferred to Belgium, and must possess specific qualifications or skills that are scarce on the Belgian labor market.

How does this affect your invoices? The short answer: it changes your tax calculation, not your invoice format. Every mandatory field described earlier in this guide — your BTW-nummer, sequential invoice number, VAT rate, line item descriptions, and so on — remains exactly the same whether you benefit from the 30% regime or not. Belgian invoicing law does not require you to reference your special tax status on the face of an invoice.

That said, the practical implications for your invoicing structure matter. You should work closely with your Belgian accountant to ensure that the way you invoice and report income correctly reflects the split between taxable remuneration and qualifying cost reimbursements when you file your annual tax declaration. If you invoice through a Belgian management company (a common setup for expat freelancers), the invoicing flow between your company and your client should be documented in a way that supports the cost allowance claim during tax audits.

One distinction worth keeping straight: the 30% expat regime is an income tax measure, while the Kleine Onderneming VAT exemption is a VAT measure. They serve entirely different purposes, and a freelancer can potentially qualify for both simultaneously — enjoying the VAT exemption on invoicing while also benefiting from the 30% cost allowance on their personal tax return. The regime has a maximum duration of five years (with possible extension to eight under transitional rules for those already in the old regime before 2022), and freelancers who lose eligibility must adjust their tax declarations accordingly, though their invoicing obligations remain unchanged.

Belgium is not the only European country offering special frameworks for international freelancers. If you also operate across borders, you may find it useful to compare Poland's freelancer invoicing requirements for JDG businesses, which take a different approach to self-employment compliance but share some of the same cross-border complexities.