Is the SNA certificate mandatory for NEN 4400?

No, the SNA certificate is not mandatory by law. It is a private certificate from the Stichting Normering Arbeid (SNA, Labour Standards Foundation). Inspection bodies assess you against NEN 4400, and SNA  adds you to the register if the result is positive. The legal obligation under the Wtta (Dutch Act on Licensing of Temporary Labour) is the approval of labour users. This is enforced from 1 January 2028, and approval runs through the Nederlandse Autoriteit Uitleenmarkt (NAU, Dutch Labour Hire Market Authority) .

In practice, the certificate can still seem mandatory, because clients often ask for it in the contract. That comes from contractual requirements, not from the law. So first read the hub on NEN 4400 and SNA and the Wtta timeline, so you know which route applies to your situation.

Last checked: 28 October 2026.

The difference in one table

What does the Wtta timeline say?

According to the government’s Wtta information , the process runs as follows. Registration for the transitional scheme runs from 1 November to 31 December 2026. The rules take effect on 1 January 2027. Applications for mandatory approval run from 1 May to 30 June 2027, and the NAU assesses applications from 1 July 2027. Enforcement by the Nederlandse Arbeidsinspectie (Netherlands Labour Authority) starts on 1 January 2028.

From that date, labour users may only operate with an approval or exemption, or if they fall under the transitional scheme. Clients may only work with such labour users. That is the legal obligation. An SNA certificate changes nothing about this.

A fictional example

Construction company Halm hires in 30 workers a year through two labour users. The contract with one of them states: “The labour user holds a valid SNA certificate.” Halm asks for the declaration and checks the register.

That is a contractual requirement, not a legal one. Halm must also check whether the labour user has applied for approval before 2028 or falls under the transitional scheme. The certificate does not replace that check. This example is fictional.

What should a client do?

1. Check your own contract to see whether the certificate is an obligation or a wish.
2. Request the declaration and check the status in the SNA register.
3. Ask which stage of the Wtta the labour user has reached: registration, application or approval.
4. Record the agreement in the contract, with a reference to the date of your check.

What should a labour user know?

If you hire out labour, keep two routes apart. The SNA process says something about your administration and inspection. Wtta approval decides whether you may hire out labour. A labour user that relies only on the certificate may not hire out labour after 1 January 2028 without approval, an exemption or the transitional scheme.

So prepare your registration for the transitional scheme now. See apply for an SNA certificate for the inspection, and costs and timeline for your own planning.

Frequently asked questions

Can I skip the Wtta with an SNA certificate?

No. The certificate and the approval are different instruments. The certificate is not the same as an approval and does not give an exemption. See Wtta and SNA.

As a client, should I only work with certified parties now?

That depends on your contract and your risk. The legal requirement for approval applies from 1 January 2028. The SNA certificate can help with your assessment, but it is not a full supplier audit.

What if my client makes the certificate mandatory?

Then it is a contractual requirement. Ask the inspection body for the current status and check it in the register. The contract sets what you must deliver, not the law.

What does this mean for a labour user already operating?

A staffing agency that has been supplying staff for years does not need to wait until 2028 to start. Registration for the transitional scheme is possible from 1 November to 31 December 2026. Anyone who registers and applies for approval or an exemption between 1 May and 30 June 2027 may keep lending while the NAU assesses the application.

In practice, this means you need to know now which activities you carry out. If you hire out workers to another company, the Wtta applies. Whether a self-employed person falls under it depends on the actual direction of the work. See the self-employed page for that boundary.

What changes for a client?

A client does not look at the certificate alone. From 1 January 2028, a client may only work with labour users that hold an approval, an exemption or a transitional scheme status. This is set out on the government’s Wtta website .

So it is sensible to check and record the status of your suppliers now. From 1 July 2027, clients can check in the NAU’s public register whether a labour user has been approved.

Common misunderstandings

• “We have a certificate, so we are done.” The certificate is an inspection result. Approval is the legal decision.
• “Only staffing agencies are affected.” The Wtta covers anyone who makes employees available to another company, including secondment agencies.
• “Our contract says certificate, so we do not need to do anything.” A contractual requirement does not replace the legal check.

Checklist for the coming months

1. Make a list of all labour users and subcontractors you currently use, with KvK number and activity.
2. Check for each party whether there is an SNA declaration and whether it appears in the register.
3. Ask each party whether and when they will apply for approval.
4. Record in your purchasing process that you check the status for every new assignment.
5. Note the dates 1 November 2026, 1 May 2027, 1 July 2027 and 1 January 2028 in your diary.

For the cost of this process, see costs and timeline. For the difference between the routes, see Wtta and SNA.

Sources

• Approval labour market: date planning and who is covered 
• SNA: the scheme