Statutory interest on commercial transactions: when it applies, how much you can charge and how to calculate it

Current interest rate

The statutory interest rate for commercial transactions is 10.5% per year.

Last updated: 16 October 2026. This rate is published every six months in the Belgian Official Gazette. Always check which interest rate applied during the period your invoice remained unpaid.

When does an invoice qualify for statutory interest on commercial transactions?

Statutory interest on commercial transactions applies to payments for goods or services between businesses, or between a business and a public authority.

If a consumer or private individual is involved, the statutory interest rate for non-commercial transactions applies instead. This is a different system with a different, generally lower rate.

The legal basis is the Belgian Act of 2 August 2002 on combating late payment in commercial transactions.

If your customer wants to dispute an invoice, that is different from an ordinary late payment.

When can you start charging interest?

For commercial transactions, interest generally starts accruing automatically from the first day after the payment due date. A separate formal notice of default is not required, provided the agreed payment deadline has clearly passed.

The applicable payment terms determine when an invoice becomes overdue and when interest may become payable.

However, this does not mean you will automatically receive the interest. In practice, you include it in your payment reminder or formal notice of default, and you must be able to demonstrate the date from which you calculate it. A correctly issued invoice with a clear due date is the starting point.

Has your customer requested a payment extension? Make clear arrangements about the new payment deadline and the consequences for any interest.

How do you calculate statutory interest?

The formula:

Outstanding amount × interest rate × number of days overdue / 365

You calculate interest proportionally based on the actual number of days the payment is overdue, rather than charging interest for an entire year.

Example for an invoice of €5,000

At an annual interest rate of 10.5%:

Keep in mind that interest compensates you for late payment, not for your debt recovery costs. A separate arrangement applies to those costs.

Charging interest is one thing, getting your invoice paid is another

Charging statutory interest can help limit the financial impact of late payments. But what if your customer still refuses to pay despite repeated reminders?

That's where Unpaid comes in. Through the RUD procedure, we help businesses legally recover outstanding, undisputed B2B invoices. Without going to court and with a bailiff visiting your customer within five working days.

When your invoice is successfully recovered, you receive 100% of your original invoice amount and your advance payment is refunded in full.

Is your invoice still unpaid?

Use our free Invoice Check to find out in just two minutes whether your invoice qualifies for recovery.

Check your chances!

Or submit your case directly through Unpaid.