What is a WIK letter?

The WIK letter is a formal demand letter that complies with the requirements of the Dutch Collection Costs Act (Wet Incassokosten, or WIK), set out in article 6:96 paragraph 6 of the Dutch Civil Code (BW). This law came into effect on 1 July 2012 and protects consumers against unreasonably high collection costs.

The core of this regulation is that you must first send the consumer-debtor a written demand giving them a final period of at least fourteen days to pay the outstanding invoice. Only after the debtor has still not paid after this period are you allowed to charge collection costs.

The WIK letter is therefore not just any demand: it is a legal prerequisite that you must fulfill before you may claim extrajudicial collection costs. Without a valid WIK letter, your right to reimbursement of these costs lapses. This has been confirmed multiple times by the Dutch Supreme Court (Hoge Raad).

A legally valid WIK letter must contain a number of mandatory elements. If you omit even one element, the letter is invalid and you cannot claim collection costs. The following elements must be included in your WIK letter:

• The creditor's details — your company name, address, and contact information.
• The debtor's details — the name and address of the person or company that owes payment.
• The invoice number and amount — a clear reference to the outstanding invoice, including the exact amount.
• A payment deadline of at least 14 days — starting from the day after receipt of the letter. The wording must explicitly state that the deadline is "fourteen days after the day on which this letter is received."
• The exact amount of collection costs — you must specifically state what amount of collection costs will be owed if payment is not made on time. A reference to "the statutory collection costs" without stating the amount is not sufficient.
• A demand for payment — an unambiguous call to pay the invoice within the stated deadline.

Stating the exact amount of collection costs is a point where many business owners make mistakes. The Dutch Supreme Court ruled in 2014 (ECLI:NL:HR:2014:3076) that a vague reference to "statutory costs" is not sufficient. You must state the specific amount.

The WIK letter fits into a clear debt collection process. Below you will find the steps you go through as a business owner when a customer fails to pay:

• Step 1: Send the invoice — You send your invoice with a payment deadline (e.g., 14 or 30 days).
• Step 2: Payment deadline expires — The customer does not pay within the agreed period. The customer is now in default.
• Step 3: Send the WIK letter — You send the 14-day demand letter. In this letter, you give the customer one final opportunity of 14 days to pay.
• Step 4: Wait 14 days — The 14-day period starts on the day after the debtor receives the letter.
• Step 5: Claim collection costs — Only after the debtor has still not paid after the 14-day period may you charge collection costs and potentially proceed with further collection measures.

It is important that you follow the entire process. If you skip a step, you risk a court rejecting the collection costs.

In practice, the terms "reminder" and "WIK letter" are often used interchangeably, but there is an important difference:

A reminder is a general term for a notice about an outstanding payment. You can send multiple reminders (first reminder, second reminder, etc.) without any specific legal requirements attached to them.

A WIK letter is a specific, legally required demand that must meet strict formal requirements. Only if your letter meets all the requirements of article 6:96 paragraph 6 BW does it qualify as a valid WIK letter, allowing you to subsequently claim collection costs.

The difference therefore lies not in the intention (both are a call to pay), but in the legal validity. An ordinary reminder without the required elements (specific collection cost amount, 14-day deadline) is legally not a valid WIK letter, even if it was intended as such.

Tip: combine your final reminder with the WIK letter. This saves you an extra step in the collection process.

Read more about the difference between a reminder and a WIK letter in our detailed blog article.

The legislator and case law have established clear requirements that a WIK letter must meet. Below is an overview of the most important points:

• Written form — The letter must be in writing. This can be by post, but also by email (see below).
• A deadline of at least 14 days — The debtor must be given at least 14 days to pay, calculated from the day after receipt. Using the phrasing "within fourteen days of the date of this letter" is insufficient, as the debtor may not receive the letter until days later.
• Specific statement of collection costs — You must state the exact amount you will charge as collection costs. A phrasing like "the legally permitted collection costs" without an amount is invalid.
• Correct calculation — The stated collection costs must correspond to the statutory scale (the Decree on Compensation for Extrajudicial Collection Costs, known as the BIK scale). You may not demand more than is legally permitted.
• Sending once is sufficient — You only need to send the WIK letter once. However, it is advisable to keep proof of dispatch.

Please note: these requirements apply specifically to claims against consumers (private individuals). For claims against businesses (B2B), different rules apply and the WIK letter is generally not required, although sending one is still advisable in B2B relationships.

The amount of collection costs you may claim is set out in the Decree on Compensation for Extrajudicial Collection Costs (BIK). This decree uses a tiered system based on the principal amount of your claim:

• On the first €2,500: 15% (minimum €40)
• On the next €2,500: 10%
• On the next €5,000: 5%
• On the next €190,000: 1%
• On any amount above €200,000: 0.5% (maximum €6,775)

The minimum amount of collection costs is always €40, even if the percentage calculation results in a lower figure. This means that for small invoices (up to approximately €267), you may always claim €40 in collection costs.

Want to know exactly how much collection costs you may charge? Use our free collection costs calculator to calculate the exact amount for your claim. You need the correct amount to draft a valid WIK letter.

Are you VAT registered? Read our article on collection costs and VAT as well.

A frequently asked question is whether you may send the WIK letter by email instead of by post. The answer is: yes, you may. The law refers to a "written demand" and case law has confirmed that email falls within this definition.

However, there are a few important considerations when sending by email:

• Burden of proof — In the event of a dispute, you must be able to demonstrate that the debtor received the email. It is advisable to request a read receipt or use a service that records delivery.
• Correct email address — Use the email address that the debtor provided when entering into the agreement, or one that has been used in previous correspondence.
• 14-day deadline — With email, the 14-day period starts on the day after dispatch, because email is delivered almost instantly. This is an advantage over sending by post, where you must account for postal delivery time.
• PDF attachment — It is recommended to attach the WIK letter as a PDF, so the debtor receives a clear and formal document.

Through wikbriefversturen.nl, you can quickly and easily send your WIK letter by email, including automatic read receipt and a professional PDF attachment. This ensures you are well protected legally.

Want to know more? Read our article on sending a WIK letter by email for a comprehensive legal analysis.

Have you sent a valid WIK letter and the debtor still hasn't paid after the 14-day period? Then you have several options:

• Charge collection costs — You may now add the previously announced collection costs to the principal amount. This amount is immediately due and payable.
• Claim statutory interest — In addition to collection costs, you can claim statutory interest over the period that the payment is overdue. For consumers, this interest rate is the percentage set annually by the government.
• Engage a collection agency — You can hire a collection agency to recover the debt on your behalf. The costs of this are borne by the debtor (up to the statutory maximum).
• Start legal proceedings — If extrajudicial collection is unsuccessful, you can initiate court proceedings before the subdistrict court (kantonrechter). For claims up to €25,000, the subdistrict court has jurisdiction. You can also recover the legal costs from the debtor.

It is advisable to carefully preserve all correspondence and supporting documents. The court will verify whether you have followed the correct collection process, including sending a valid WIK letter.