A1 verklaring aanvragen (applying for an A1 certificate) works like this: a Dutch employer logs in to TWinternet at the SVB (Sociale Verzekeringsbank, the Dutch social insurance bank) with eHerkenning at level EH3 and submits the application, before the employee starts working in Belgium. It is free. A complete TWinternet application can often be approved straight away; if the SVB needs more information, or you apply on paper, allow 6 to 8 weeks or more. The A1 proves that your employee stays insured in the Netherlands. It does not replace the Belgian Limosa declaration or registration in Checkinatwork on Belgian construction sites.
Suivo is a Belgian company that supports contractors with Check in at Work registration on Belgian sites. Below is the Dutch side of the paperwork: the SVB process, step by step.
When does a Dutch employer need an A1 for Belgium?
An A1 certificate shows that a worker who works temporarily outside the Netherlands stays covered by Dutch social insurance. It exists only for work in an EU or EEA country (including Switzerland) or a treaty country. Belgium is an EU country, so postings there are in scope.
Typical situations for Dutch construction and technical firms:
- A crew builds or renovates on a Belgian site for a few months.
- A service engineer carries out an installation job for a Belgian client.
- A Dutch concrete company delivers and pumps concrete on Belgian sites.
According to the SVB, a detachering (posting) to an EU/EEA country may last 24 months. If the work continues after that, the SVB can make an agreement with the Belgian authority, which must agree. The SVB says a posting can sometimes be extended to up to 5 years this way. If the work abroad has no agreed end date, the worker is no longer insured in the Netherlands but in the country of work.
Before you apply, run the SVB’s online check (Bekijk of uw werknemer verzekerd blijft). It looks at, among other things, whether the posting is temporary, whether the worker stays employed by you, whether you keep paying the salary, and his nationality.
How do you apply with the SVB, step by step?
The SVB is the only issuer. The UWV (the Dutch employee insurance agency) refers applicants to the SVB. Some companies offer to request A1s for a fee; the SVB says that is unnecessary.
| Step | What you do | What you need |
|---|---|---|
| 1. Check | Use the SVB check to see if your employee stays insured in the Netherlands | Posting details |
| 2. TWinternet account | Request an account for your establishment | KVK number, establishment (vestigingsnummer) number, loonheffingennummer (payroll tax number) |
| 3. eHerkenning | Get eHerkenning at level EH3 from a government-recognised supplier | Required since 25 April 2023 |
| 4. Authorisations | Authorise staff who apply, via your eHerkenning supplier; for an intermediary, arrange a chain authorisation (ketenmachtiging) | eHerkenning management module |
| 5. Apply | Submit the application in TWinternet, before the work starts | Employee and posting details |
| 6. Receive | The SVB issues the A1 once and sends the original to the employee | Keep a copy for your records |
| 7. Extend | Report a longer posting as an extension in TWinternet | Existing A1 |
Practical notes:
- One TWinternet account per establishment. A company with several branches needs an account for each.
- Only Dutch-established companies can apply online. A foreign company applies on a paper form by post.
- No e-mail applications. The SVB does not accept them.
- The original goes to the employee. The employee can authorise you to receive it. In TWinternet you can create a PDF of all approved A1s, which is useful for site files.
- Self-employed persons and DGAs (director-major shareholders) do not use TWinternet. They apply via Mijn SVB.
How long does it take, and what do you do while you wait?
According to the SVB’s step-by-step page, processing takes 6 to 8 weeks. That page describes the Mijn SVB and paper route. For employer applications in TWinternet, the SVB says it can often finish the application straight away if the posting period is correct and the employee meets all conditions. If the SVB needs more information, it can take longer. The SVB’s A1 application page adds that for work abroad of more than 2 years, it does extra research and the form usually arrives within 3 months.
Work backwards from the start date:
- 8 weeks or more before the start: submit the application.
- Before the start: make sure the Belgian formalities (Limosa, Checkinatwork) are in order too.
- First day on site: the employee carries the A1, or a copy of the application if the A1 has not arrived yet.
If the job starts before the A1 arrives: the SVB says that in most countries the inspection services accept a copy of the A1 application. If they do not, contact the SVB, which will consider urgent handling. The A1 is valid for the period for which it was issued, unless it is withdrawn.
What if your staff work in several countries?
A fitter who works in both the Netherlands and Belgium every week is not a posted worker. A different rule applies. According to the SVB, a person who works for one employer in several EU countries is insured in his country of residence if he works at least 25% of his working time there. Otherwise he is insured in the country where the employer is established.
- The 24-month posting limit does not apply to this situation. The 25% test does.
- The worker reports multi-country work to the social security institution of his country of residence. For people living in the Netherlands, that is the SVB.
- For workers living outside the Netherlands (for example a Belgian resident on your payroll), you first need a decision from the institution in his country of residence, and then you apply to the SVB on paper.
To prove the 25%, you need reliable records of where each person worked. A registration that captures the site for every working day makes this far easier than rebuilding it from memory.
What is the risk without an A1?
The SVB warns that in many countries the labour inspectorate checks whether a worker is socially insured, and that without an A1 the worker may not work in some countries. According to Ondernemersplein (the Dutch government’s business portal), you can get a fine from the labour inspectorate in the country where the work takes place.
For how Belgian inspectors check the A1 on site, read our A1 certificate guide for Belgium.
Why is an A1 not enough? Limosa and Checkinatwork still apply
The A1 settles which country’s social security applies. Belgium has its own formalities on top. Belgian FPS Employment distinguishes posting under labour law (the Limosa declaration by the foreign employer before work starts) from posting under social security (the A1). You need both.
| Document | Country | What it covers | When |
|---|---|---|---|
| A1 verklaring | Netherlands (SVB) | Your employee stays insured in the Netherlands | Apply before the work starts |
| Limosa declaration | Belgium | Declaration of foreign workers in Belgium | Before activities start |
| Checkinatwork registration | Belgium | Daily attendance on construction sites above the threshold | Every day, before work starts |
Limosa. According to Belgian social security, a person who comes from abroad to work temporarily in Belgium must be able to show a Limosa-1 receipt before the activities start. The Belgian client must check the L1 before work starts. If it cannot be shown, the client must report the missing L1 to the RSZ electronically before work starts, otherwise sanctions can follow. Some situations are exempt, such as short meetings or urgent repairs: check them on the Working in Belgium site. Our Limosa declaration guide explains the process.
Checkinatwork. Check in at Work applies to works in immovable state and to the delivery of ready-mix concrete on sites with a total value of at least EUR 500,000 excluding VAT. Attendance must be registered daily, before the person starts work. Employers and contractors register their own employees and their subcontractors. The Limosa-1 contains a QR code that can be used to register workers in Checkinatwork.
From 1 April 2027, according to the RSZ, this changes. For works in immovable state and ready-mix concrete deliveries, attendance moves to Check in and out at work (CIAO): registration on arrival and on departure. Under the CIAO rules already in force for cleaning, workers register themselves in real time (for example with a smartphone or a badge), and the employer cannot register them in advance. The RSZ has said that more practical details for construction will follow. If your Belgian project runs past 1 April 2027, plan for this now. Our 2027 compliance calendar for foreign contractors lists the dates.
Suivo’s Check in at Work solution offers three registration methods: the Check In at Work app, a mobile site pole that accepts the Belgian ID card and other identifiers, and a black box in the vehicle. For the full Belgian picture, see our Checkinatwork guide for Dutch companies and our overview for Dutch companies working in Belgium.
Frequently asked questions
How do I apply for an A1 verklaring?
As an employer established in the Netherlands, you apply online with the SVB via TWinternet, using eHerkenning at level EH3. Foreign companies apply on a paper form by post. An application by e-mail is not possible.
Is an A1 verklaring mandatory?
The SVB advises applying before the employee starts working abroad. In many countries the labour inspectorate checks whether a worker is socially insured, and without an A1 the worker may not work in some countries. You can also get a fine from the labour inspectorate in the country of work.
Who must apply for an A1 document?
For employees, the employer applies via TWinternet. Self-employed persons and DGAs (director-major shareholders) apply via Mijn SVB. A person who works in several EU countries reports this to the social security institution of his country of residence, which is the SVB if he lives in the Netherlands.
How long does an A1 verklaring application take?
A complete TWinternet application can often be approved straight away. If the SVB needs more information, or you apply on paper, allow 6 to 8 weeks or more. For postings longer than 2 years, the SVB does extra research and the form usually arrives within 3 months.
Does an A1 verklaring replace the Belgian Limosa declaration?
No. The A1 covers Dutch social security; Limosa is the Belgian declaration of foreign workers. For work in Belgium you need both, and on construction sites above the threshold you also need to register attendance in Checkinatwork.
Get the Belgian site side right from day one
The A1 is the easy part: one application, free, at one Dutch body. The daily work starts on the Belgian site, where every worker and subcontractor must be registered before work begins, and from April 2027 on arrival and departure. A registration that happens at the site gate, not in the office afterwards, keeps your crews working and your client out of trouble.
Want to see how Suivo handles attendance registration on Belgian construction sites? Book a free demo
