Cross-border work across the EU sounds simple. In practice, it triggers a question many employers overlook: which country collects the social security contributions? A1 certificates answer that question. Without one, posted workers and multi-state employees risk double charges, fines, and project delays. Here is what you need to know.
What is an A1 certificate and who needs one?
An A1 certificate proves that an employee remains covered by the social security system of their home country while working abroad in the EU, EEA, or Switzerland. It is issued under EU Regulation 883/2004 on the coordination of social security systems. Therefore, only one country collects contributions at a time. Posted workers, multi-state employees, and self-employed professionals all need A1 certificates when they cross borders for work. Employers must apply before the assignment starts, not after the worker arrives on site.
When do you need an A1 certificate?
You need an A1 certificate whenever an employee works temporarily in another EU/EEA member state or Switzerland, or works regularly in two or more countries. The rule applies to short trips, long postings, hybrid roles, and even one-day client meetings if local authorities can request proof on the spot. Many EU countries now run strict on-site inspections.
Typical situations that trigger A1 certificates include:
- Posting a Dutch employee to Germany, France, or Italy for a project
- Sending consultants to client offices across the EU
- Hiring a remote worker who splits time between two EU countries
- Self-employed contractors taking cross-border assignments
- Drivers, technicians, and engineers travelling for service work
How to get the certificate in the Netherlands
In the Netherlands, the SVB (Sociale Verzekeringsbank) issues A1 certificates. Employers apply online through the SVB portal using eHerkenning. The standard processing time is around four to six weeks, but straightforward applications often arrive sooner. As a result, employers should apply at least two months before the assignment starts.
To speed up the A1 certificate application, prepare the following before submitting:
- Employer details, including KvK number and wage tax number
- Employee identity details and BSN
- Assignment country, start date, and expected end date
- A clear description of the work and the host company
- Confirmation that the employee stays on the Dutch payroll
Incomplete files cause most delays. Therefore, double-check every field before submission.
Posted workers vs multi-state employees: what is the difference?
Posted workers and multi-state employees both need a certificate, yet the rules differ, since posted workers are sent temporarily to one other country, usually for up to 24 months. Multi-state workers split time across two or more EU countries on a regular basis. The applicable social security country depends on residence and the share of work performed.
| Aspect | Posted worker | Multi-state employee |
| Duration | Up to 24 months in one host country | Ongoing, no time limit |
| Legal basis | Article 12 of Regulation 883/2004 | Article 13 of Regulation 883/2004 |
| Social security country | Home country of employer | Country of residence if 25%+ work performed there |
| Typical example | Dutch engineer on a six-month German project | Sales manager working three days NL, two days BE |
What happens without an A1 certificate?
Without a valid A1 certificate, host country authorities can demand local social security contributions. Consequently, employers may pay twice for the same employee. Fines vary by country but often run into thousands of euros per inspection. Some host states also block site access until proof is shown.
Beyond financial risk, missing certificates cause reputational damage with clients and delays on project timelines. Audits in France, Germany, Belgium, and Austria are particularly strict. For long postings, retroactive corrections are slow and expensive. In short, the certificates are not optional paperwork. They are mandatory proof of compliance.
How Octagon helps with A1 certificates and posted workers
Octagon Professionals International supports employers with the full lifecycle of cross-border employment. We prepare A1 certificate applications, coordinate with the SVB, and manage posted worker registrations in host countries. In addition, we advise on payroll set-up, tax position, and compliance reviews. With 38+ years of experience and presence across the Netherlands, Italy, France, Germany, Cyprus, and the UK, our team handles complex cases that generalist providers often refuse. Visit Octagon Professionals to discuss your cross-border setup today.
Frequently asked questions
How long is an A1 certificate valid?
An A1 certificate for a posted worker is normally valid for up to 24 months. Multi-state worker certificates can run for longer, often up to five years, depending on the situation. The exact period appears on the certificate itself and reflects the planned assignment duration.
Can you apply for an A1 certificate after starting work abroad?
Yes, retroactive applications are possible but risky. Host country inspectors can still issue fines for the period without proof. Therefore, employers should always apply before the cross-border assignment begins. The SVB allows late submissions, yet processing them takes longer and may attract additional scrutiny.
Do business travellers need an A1 certificate for short trips?
Yes, even short business trips inside the EU technically require an A1 certificate. Countries such as France and Austria run strict checks on day visits. A multi-state A1 covering all EU travel is the simplest solution for frequent travellers. It avoids constant new applications for each short trip.
Who pays for A1 certificate applications in the Netherlands?
The SVB issues A1 certificates free of charge. However, employers carry the administrative cost of preparing accurate applications. Mistakes lead to delays and rejections. Many companies outsource this work to specialists like Octagon to avoid wasted time and ensure each application clears the SVB on first submission.
