Late-payment interest in Belgium: legal and commercial rates

The rule in brief

• Legal interest (law of 5 May 1865, art. 2, § 1): one rate per calendar year, 4.50 % in 2025 and in 2026. In civil matters it runs from the formal notice, unless the law or the contract makes it run automatically (Civil Code art. 5.240).
• Commercial late-payment interest (law of 2 August 2002, art. 5): one rate per half-year, 10.50 % for both halves of 2026. Between enterprises, and with public authorities, it runs automatically from the day after the payment term.
• A €40 flat compensation is due automatically, per invoice paid late, whenever commercial interest is due (art. 6).
• A partial payment goes first to the interest, then to the principal (Civil Code art. 5.210).
• Interest is computed period by period: the rate of each calendar year (or half-year) applies to the days of that year, not the rate of the day of the formal notice.

The interest calculator applies these rules and exports the statement to PDF, Word and CSV.

Legal interest: law of 5 May 1865

How the rate is set

The legal rate (taux d'intérêt légal / wettelijke intrestvoet) is the average 12-month Euribor of December of the previous year, rounded up to the next quarter point, plus 2 points (art. 2, § 1, as amended by the programme law of 27 December 2006). It applies from 1 January to 31 December.

Before 2007, a royal decree fixed the rate (7 % from 2002 to 2006); the formula then gave 6 % in 2007, 7 % in 2008 and 5.50 % in 2009. The 2027 rate is not published yet: for a period running into 2027, the tool says so and you can enter a contractual rate instead.

When it starts

Moratory interest (intérêts moratoires / moratoire intrest) runs from the formal notice (mise en demeure / ingebrekestelling), unless the law or the contract makes it run automatically (Civil Code art. 5.240). The tool takes the first day of interest and the last day (payment or day of the statement), both included. Each period's interest is principal × rate × exact number of days ÷ 365, rounded to the cent. No text sets that day basis: it is the practice, and the statement says so.

Commercial late-payment interest: law of 2 August 2002

Scope and payment terms

The law of 2 August 2002 on combating late payment covers transactions between enterprises and between enterprises and public authorities. It does not cover consumer debts. Interest runs automatically, without formal notice, from the day after the payment term: 30 days by default, at most 60 days by contract. With a public authority, the term is 30 days, at most 60 when objectively justified, and health bodies have 60 days. A public authority pays the same rate as an enterprise and cannot agree a different one.

The half-yearly rate

The rate is the ECB main refinancing rate on 1 January (first half-year) or 1 July (second half-year), plus 8 points, rounded up to the next half point (art. 5).

For the second half of 2026: ECB rate of 2.40 % (from 17 June 2026) + 8 = 10.40 %, rounded up to 10.50 %.

Contracts concluded from 7 August 2002 to 15 March 2013. Their payments followed the old rule (ECB rate + 7 points, rounded up to the next half point) until 15 March 2015: for example 7.50 % in 2014. From 16 March 2015, the general rate and the €40 compensation apply to them too (law of 22 November 2013, art. 12). The calculator has a separate option for these contracts; contracts concluded before 7 August 2002 are not covered.

The €40 flat compensation

Whenever interest is due under art. 5, the creditor is entitled to a flat compensation for recovery costs of €40, automatically and without formal notice (art. 6). The Court of Justice of the European Union held that it is due for each invoice paid late, even when several invoices are claimed together (20 October 2022, C-585/20); the VAT on the invoice is part of the amount due on which interest runs. Reasonable compensation for recovery costs above €40 can also be claimed. A clause excluding the interest is deemed grossly unfair, and a clause excluding the compensation is presumed to be (art. 7).

Partial payments and interest on interest

Under Civil Code art. 5.210, a partial payment is imputed first on the interest due, then on the principal. The tool splits the statement at each payment: interest stops on the day before the payment, the payment clears the accrued interest, and the remainder reduces the principal on which the next period runs. A payment above everything owed is shown as a surplus.

Interest due bears interest itself (capitalisation, anatocism) only after a written formal notice or under a specific contract, and only for interest due for at least a full year (Civil Code art. 5.207). The tool does not compute it.

What the tool does not cover

• Consumer debts. Book XIX of the Code of Economic Law, applicable since 1 September 2023, caps late-payment interest and damages owed by consumers (a free first reminder, flat amounts by size of the debt). Those rules were not researched for the tool: check them before claiming anything from a consumer.
• Tax interest.
• Interest on interest.
• A statement of several invoices, each with its own start date, is a firm feature (free with a verified e-mail address); it does not compute partial payments.

Worked examples

Legal rate across a change of year

A civil claim of €10,000, with moratory interest from 1 July 2024 (formal notice) to 30 June 2025.

Applying the 2024 rate to the whole year would overstate the interest: the 2025 days carry the 2025 rate.

A partial payment

€10,000 at the legal rate from 1 January 2025; €1,000 paid on 1 July 2025; statement on 31 December 2025.

• 1 January to 30 June 2025: 181 days at 4.50 % on €10,000 = €223.15.
• The €1,000 payment: €223.15 to the interest, €776.85 to the principal, which falls to €9,223.15.
• 1 July to 31 December 2025: 184 days at 4.50 % on €9,223.15 = €209.23.
• Due on 31 December 2025: €9,223.15 + €209.23 = €9,432.38.

A commercial invoice in 2026

An invoice of €8,000 between two enterprises; the payment term expired on 1 April 2026. Interest runs from 2 April 2026, statement on 30 September 2026.

• 2 April to 30 June 2026: 90 days at 10.50 % = €207.12.
• 1 July to 30 September 2026: 92 days at 10.50 % = €211.73.
• Interest €418.85 + flat compensation €40 = €8,458.85 due.

Across the mid-2025 change, €5,000 from 1 May to 31 August 2025 gives €96.10 (61 days at 11.50 %) and €89.18 (62 days at 10.50 %): €185.28, plus €40.

Check your own statement with the interest calculator. For the costs of the proceedings to recover the debt, see the guide on litigation costs and the client cost estimate, which adds legal interest over the expected length of the case.

Common mistakes and open points

• Freezing the rate. The legal rate is that of each calendar year in which interest accrues, not that of the formal notice.
• Claiming commercial interest from a consumer. The law of 2 August 2002 does not apply; Book XIX of the Code of Economic Law does.
• Forgetting the €40. It is due per invoice paid late, without formal notice, as soon as commercial interest is due.
• Imputing a payment on the principal first. Art. 5.210 imputes it on the interest first.
• Publication not seen. The 2026 legal rate and the commercial rates from the second half of 2025 rest on concordant secondary sources and the statutory formula; their publication in the Belgian Official Gazette was not seen.

The tool assists the lawyer, who remains responsible for the calculation and for checking the applicable rule.

Sources

• Law of 5 May 1865, art. 2, § 1 (as amended by the programme law of 27 December 2006): legal interest rates published by the FPS Finance. Verified on 5 October 2026.
• Law of 2 August 2002 on combating late payment in commercial transactions, arts. 5, 6, 7 and 14, as amended by the law of 22 November 2013: FPS Justice press release of 18 July 2013. Verified on 5 October 2026.
• ECB main refinancing rate from 17 June 2026: Banco de España notice. Verified on 4 October 2026.
• Court of Justice of the European Union, 20 October 2022, C-585/20, BFF Finance Iberia. Verified on 5 October 2026.
• Civil Code, Book 5, arts. 5.207, 5.210 and 5.240. Verified on 4 October 2026.