Calculating statutory interest: rates & examples

When an invoice is not paid on time, you as a creditor have the right to statutory interest. This is compensation for the damage you suffer by having to wait longer for your money. But how exactly do you calculate this interest? What percentage applies in 2026? And what is the difference with commercial interest? In this article we explain everything step by step, so you know exactly what you are entitled to and how to correctly calculate statutory interest.

Statutory interest is the interest a debtor owes when they pay late. It is a legally determined interest rate that serves as compensation for the creditor. Statutory interest is regulated in the Dutch Civil Code (Burgerlijk Wetboek, or BW) and comes in two variants:

• Regular statutory interest (art. 6:119 BW): the standard statutory interest that applies in all cases where a debtor is in default. This applies, among other things, to claims on consumers (private individuals).
• Commercial statutory interest (art. 6:119a BW): a higher interest rate that specifically applies to commercial transactions — that is, transactions between businesses or between businesses and government institutions. This is also referred to as commercial interest or trade interest.

The key difference is that commercial interest is considerably higher than regular statutory interest. The legislator has deliberately set it this way to encourage businesses to pay other businesses on time, in accordance with the European Directive on combating late payment in commercial transactions.

The level of statutory interest is periodically determined by government decree (Algemene Maatregel van Bestuur). Regular statutory interest is adjusted every six months, and commercial interest is adjusted twice a year based on the refinancing rate of the European Central Bank (ECB), plus 8 percentage points.

The current rates are:

Please note: these rates apply on an annual basis. If you calculate the interest over a shorter period, you must apply the rate proportionally (see the calculation examples below). Always check the most recent rates, as they may change twice per year.

Historically, regular statutory interest has fluctuated between 2% and 8% in recent years. Commercial interest has consistently been significantly higher, typically between 8% and 12.50%. The current rates reflect the ECB’s higher interest rate policy.

It is essential to know which type of interest you may claim. Applying the wrong rate can result in a judge rejecting or reducing your interest claim. Below is an overview of when each type of interest applies:

• Statutory interest (4%): applies to claims on consumers (private individuals). For example, an invoice for a service you provided as a business to a private individual. This rate also applies to other obligations that do not qualify as commercial transactions, such as damages.
• Commercial interest (10.15%): applies to claims between businesses (B2B) or between a business and a government institution. Requirements: both parties must be acting in the course of a profession or business, and the agreement must relate to the delivery of goods or the provision of services for payment.

A common mistake is claiming commercial interest on a consumer claim. This is not permitted. Conversely, you are leaving money on the table if you only claim regular statutory interest on a business claim, when you are entitled to the higher commercial interest rate.

The formula for calculating statutory interest is as follows:

Let us illustrate this with a concrete calculation example:

As you can see, the type of interest makes a significant difference. For a business claim, the interest is more than twice as high. It is therefore important to apply the correct interest rate.

Please note: if the interest rate has changed during the period of default (because the ECB has adjusted the rate), you must apply the applicable rate for each sub-period. For long-standing claims, the rate may therefore change multiple times.

Statutory interest starts accruing as soon as the debtor is in default. When exactly that is depends on the situation:

• Fatal payment term: if a final payment date has been agreed (for example “pay within 30 days”), then default occurs automatically on the day after the term expires. From that moment, statutory interest starts accruing.
• No payment term agreed: if no payment term has been agreed, you must first send the debtor a formal notice of default. Only after the reasonable term stated in the notice of default has expired is the debtor in default and does the interest start accruing.
• Commercial transactions: for commercial transactions, pursuant to art. 6:119a BW, commercial statutory interest is automatically owed from the day after the final payment date. If no payment term has been agreed, a statutory term of 30 days after receipt of the invoice applies.

When sending a WIK letter (14-day letter), the debtor is given 14 days to pay after receipt of the letter. However, statutory interest does not only start after these 14 days. The interest accrues from the moment of default, i.e. from the expiry of the original payment term. The WIK letter is a requirement for charging collection costs, but has no influence on the start date of the interest.

This is an important distinction: statutory interest and collection costs each have their own starting point. Interest accrues from the moment of default; the right to collection costs only arises after the 14-day term from the WIK letter has expired.

A frequently asked question is whether you may claim both statutory interest and collection costs. The answer is: yes, you may. They are two separate items that exist alongside each other. Statutory interest is compensation for late payment; collection costs are compensation for the costs you incur to collect the amount.

Your total claim in case of non-payment therefore consists of three components:

The collection costs in the example above are calculated according to the BIK scale: 15% on the first € 2,500 (€ 375) plus 10% on the next € 2,500 (€ 250) = € 625. Use our collection costs calculator to calculate the exact amount for your situation.

Please note: you calculate statutory interest on the principal amount, not on the principal plus collection costs. Collection costs are calculated separately based on the BIK scale. Want to know more about collection costs and VAT? Read our article on this topic.

Additionally, statutory interest continues to accrue until full payment is made. If the debtor pays after 120 days instead of 60, the interest doubles. It is therefore in your interest to act quickly in case of non-payment. The sooner you send a correct demand letter, the sooner the collection process can begin.

Calculating statutory interest is not complicated, but it is important to apply the correct rate. For claims on consumers, the statutory interest rate of 4% applies (art. 6:119 BW); for business claims, the commercial interest rate of 10.15% applies (art. 6:119a BW). Interest accrues from the moment of default and you may combine it with collection costs.

Use the formula Principal × Interest rate × (Days ÷ 365) to calculate the amount, and account for any interim changes to the rate. Do not forget that in addition to interest, you can also claim collection costs if you have sent a correct WIK letter. Read more about the difference between a reminder and a WIK letter.

At wikbriefversturen.nl you can send a legally correct WIK letter within two minutes based on your invoice details — you can even send it by email. This secures your rights and, in case of continued non-payment, allows you to claim both statutory interest and collection costs. Considering a collection agency? Read our comparison first.