What Is an A1 Certificate and When Do Your Employees Need One?

Your Head of Engineering wants to send three developers to the Netherlands for a six-week implementation project. Your CFO asks a simple question: "Where do we pay social security for those months?" And suddenly you're down a rabbit hole of EU coordination rules, portable documents, and acronyms nobody explained during your HR certification.

The A1 certificate is the answer to that question, and understanding it matters more than most mid-market companies realise. An A1 Certificate is an EU social security coordination document that confirms which country's social security legislation applies to a worker who performs work in one European country while remaining insured in another. It's the proof that keeps you from paying contributions in two countries for the same work period.

For companies with 200 to 2,000 employees running cross-border projects across Europe, A1 certificates sit at the intersection of compliance, cost control, and operational efficiency. Get them right, and your teams move freely across borders with clear documentation. Get them wrong, and you're facing retroactive contribution demands, inspection findings, and the kind of administrative chaos that derails project timelines., with 5.5 million A1 attestations issued in 2023 alone.

Quick Facts: A1 Certificates

• An A1 certificate of coverage confirms which country's social security rules apply when your employee works temporarily in another EU, EEA country, or Switzerland
• The A1 Certificate operates under EU social security coordination rules covering 27 EU Member States plus Iceland, Liechtenstein, Norway, and Switzerland
• A1 coverage is time-bound and issued for a defined start and end date rather than indefinite coverage
• The certificate addresses social security only, not income tax residence, immigration status, or employment law
• Mid-market organisations with 200 to 2,000 employees typically need an A1 tracking register once they have frequent travel patterns across 3 or more European countries
• For audit readiness, Teamed recommends retaining A1 certificates and supporting posting records for at least 6 years

What an A1 Certificate of Coverage Is and Why It Exists

A certificate of coverage is a government-issued confirmation of applicable social security legislation for cross-border work, used to prevent double social security contributions during a defined period. The A1 certificate is the specific version used within Europe.

In practice, the A1 certificate is your proof that social security is still paid at home even when work is done abroad.

Here's what it does: confirms the applicable social security system, avoids double contributions, and provides evidence during inspections. Here's what it doesn't do: decide income tax residence, replace visas or immigration permissions, or change your employment contract.

Social security in this context means state-administered insurance covering pensions, sickness benefits, unemployment insurance, and family benefits. When an employee works in another EU country without an A1, the host country can require local social security registration from day one. The A1 prevents that overlap.

A posted worker is an employee who is sent by their employer to perform work temporarily in another EU, EEA country, or Switzerland while remaining employed and normally insured in the sending country. This is the scenario the A1 was designed for.

Consider a French consulting firm sending a team to deliver a three-month project in Germany. Without A1 certificates, German authorities could demand local registration and contributions. With them, everyone stays under the French system for the duration.

When Employees Need an A1 Certificate for Work in Europe

The core rule is straightforward: if an employee affiliated to social security in one EU, EEA country, or Switzerland performs work physically in another, an A1 is generally needed. Even for short durations. Inspectors can ask for proof, and "it was only a week" isn't a defence.

Typical scenarios requiring an A1 include client site visits and on-site delivery, implementation and installation projects, construction and engineering work, secondments, conferences where work is performed (speaking, training, technical support), regular cross-border commuting, and routine remote work from another country.

In Teamed's mobility process benchmarking, the most common operational failure mode is applying for A1 coverage after travel has started rather than before the first day of work in the host country., despite EU rules requiring application before the assignment begins.

The requirement is tied to where work is physically performed, not where the employer is registered or where customers are located. A UK-based manager meeting clients in France needs an A1. A German engineer posted to the Netherlands for a six-month project needs an A1. A Spanish sales team travelling monthly to Italy needs A1s for each trip.

Very short or occasional trips, mixed roles with limited hands-on work, and purely passive attendance at events sit in greyer territory. These warrant careful assessment rather than assumptions.

Self-employed individuals may need their own A1 certificates, but the risk concentrates around employees where the employer bears responsibility for compliance.

Which Countries Use the A1 Certificate for Social Security Coverage

The A1 framework is European-only and does not apply to assignments outside the EU, EEA, and Switzerland corridor, where bilateral social security agreements or other coverage certificates are required.

The A1 rules cover all 27 EU member states, the three EEA countries (Iceland, Liechtenstein, and Norway), and Switzerland. That's the integrated European market where social security coordination applies.

Post-Brexit, the UK and EU apply social security coordination through separate agreements. UK employers may still use A1-style certificates for EU postings, but the process runs through the EU-UK Trade and Cooperation Agreement rather than internal EU rules. Check current guidance for each specific route.

For assignments to the United States, Singapore, or other non-European destinations, different frameworks apply. Some countries have bilateral social security agreements with individual EU states. Others have no coordination at all.

You'll encounter different terms across countries: A1 Formular in Germany, A1 formulier or A1 certificaat in the Netherlands. Same document, different languages.

The A1 certificate is a European tool. It does not solve social security questions in the rest of the world.

How an A1 Certificate Affects Where Social Security Contributions Are Paid

Social security contributions are statutory employer and employee payments that fund state benefits such as pensions, sickness benefits, unemployment insurance, and certain family benefits in a specific jurisdiction. The A1 determines which jurisdiction receives those payments.

With an A1 certificate, contributions remain payable in the home country named on the certificate. The host country should not require local social security registration for the covered period. The employment contract stays unchanged; only the social security affiliation is confirmed.

Without an A1, host authorities may require local registration from day one. They can seek retroactive contributions. You risk parallel obligations and significant administrative burden.

For auditors, the A1 certificate is often the difference between a clean inspection and a demand for retroactive social contributions.

A1 coverage is not an income tax document and does not determine corporate tax permanent establishment exposure, a separation of scopes that Teamed highlights as a common source of compliance confusion in Europe and UK expansions.

Consider a Polish employee posted to Germany for a four-month implementation project. With an A1, they remain under Polish social security. Your payroll continues as normal. Without one, German authorities could demand registration under the German system, potentially requiring contributions at German rates (which differ from Polish rates) and creating administrative complexity your payroll team didn't budget for.

How to Apply for an A1 Certificate or A1 Form in the EU

The employer typically applies through the home-country social security institution's portal. Self-employed individuals can apply themselves where applicable.

The process follows a predictable pattern:

1. Gather internal details: employer information, employee information, assignment details, timelines, host countries, and work description
2. Confirm the employee's ongoing home-country affiliation and the employer's substantial activity at home
3. Complete the A1 form via the home authority's process or portal
4. Submit supporting evidence as requested (operations, revenue, staff presence documentation)
5. Track application status and store the issued certificate centrally

Data you'll need includes employer and employee details, home social security affiliation numbers, host country or countries, start and end dates, nature of work, and evidence of substantial home operations.

Processing times vary by country and case complexity. Plan ahead for frequent postings rather than scrambling at the last minute.

If you have employees based in multiple home countries, you'll need to apply through each relevant authority. A German employee and a Dutch employee on the same project to France require applications to German and Dutch authorities respectively.

Typical Duration, Renewal, and Validity Rules for A1 Certificates

The A1 Certificate is time-bound and is issued for a defined start and end date rather than indefinite coverage. This is a feature, not a bug. The certificate must reflect actual working patterns.

If assignments extend or patterns change materially, apply for an extension or a new certificate. Don't assume automatic rollovers.

Some countries require separate posting notifications or related filings with different validity rules. The A1 handles social security; other obligations may have their own timelines.

In Belgium, Germany, and the Netherlands, inspectors may ask for evidence that the A1 still matches current arrangements. An expired certificate or one that doesn't align with actual work patterns creates problems.

Good housekeeping means maintaining a central register of A1s with start and end dates, setting calendar reminders well before expiry for review and renewal, cross-checking certificates against actual travel and work patterns, and coordinating with project managers on timeline changes.

Risks for Companies When Employees Work Without an A1 Certificate

An A1 Certificate is commonly requested during on-site inspections in high-enforcement markets for posted workers, and Teamed treats it as a standard "site-ready" document for regulated-sector projects.

Financial risks include retroactive host social contributions, penaltiesFinancial risks include retroactive host social contributions, penalties ranging from €4,000 to €8,000 per employee in France, and potential double contributions. Legal and compliance risks include host registration obligations, fines, and inspection findings. Operational risks include work stoppages, delays at client sites, and administrative burden to remediate. Reputational risks matter especially in construction, engineering, and consulting where clients and tender processes increasingly require evidence of compliant posting practices.

Uneven A1 usage across similar roles raises audit questions. If some employees on similar assignments have certificates and others don't, inspectors will want to know why.

Authorities increasingly look at where the real work is happening, not only what your contracts say.

The A1 generally applies to employees. Inability to obtain an A1 for someone who functions like an employee abroad can expose misclassification risk. If the relationship doesn't fit the posting model, that's a signal worth investigating.

How Mid-Market Companies Use A1 Certificates Within Global Employment Models

A1-covered postings differ from EOR employment in that the worker remains employed by the sending employer under the home arrangement with social security staying in the home system, whereas EOR employment places the worker on host-country payroll and host-country social security.

The typical journey for scaling companies starts with A1-covered postings for early projects, then evolves to local hires via entities or Employer of Record as activity grows.

A1 works best for temporary postings where the employee's centre of life and the employer's substantial activity remain in the home country. It's designed for defined assignments, not permanent relocations or multi-country regular work.

An Employer of Record (EOR) is a third-party organisation that becomes the legal employer for a worker in a specific country, running local payroll, statutory benefits, and employment compliance while the client company directs day-to-day work. Local employment via an owned entity is a hiring model where the company employs workers through its own registered legal entity in the host country.

A1 certificates are a useful tool, but they are not a long-term global employment strategy on their own.

Consider a German SaaS company initially posting sales engineers to France and Spain with A1 certificates. As those markets become core revenue drivers with recurring work, the posting model stretches beyond its intended scope. That's when the shift to EOR or entity establishment makes sense.

Choosing Between A1 Certificates, Local Employment, or Employer of Record

Choose an A1-covered posting when an employee will work physically in another EU, EEA country, or Switzerland for a temporary, defined assignment while remaining employed and normally insured in the home country.

Choose local employment via an owned entity when the role is intended to be permanent in the host country or when the company expects an ongoing in-country footprint requiring stable local HR, payroll, and benefits administration.

Choose an Employer of Record when you need lawful local employment in the host country within weeks and you don't yet have, or don't want to establish, a local entity for that market.

The decision factors include compliance risk tolerance, total cost of employment (including social security and benefits), employee experience and benefits alignment, and speed to hire versus operational complexity.

The right answer is rarely all A1, all EOR, or all entities. It's usually a mix that evolves as your footprint grows.

A Netherlands-to-Germany project series might begin with A1 postings. When presence becomes strategic and recurring, the shift to EOR or a German entity makes sense. Teamed can model these country-specific trade-offs and execute through contractors, EOR, or entities across 180+ countries.

Practical A1 Compliance Checklist for Companies with 200 to 2,000 Employees

CFO-led cost reviews in mid-market firms typically flag A1 governance when cross-border work exceeds 10 employee-trips per month because manual, email-based processes become hard to audit.

Understand your cross-border work: Map where employees actually work and travel. Identify all roles crossing borders and their frequency and duration. Define situations that should always trigger an A1 application.

Standardise your A1 process: Establish an internal request and approval workflow with clear ownership across HR, Payroll, and project leads. Document required data and evidence. Maintain a central repository. Plan timelines to avoid last-minute applications.

Track validity and evidence: Maintain an A1 register with validity dates and linked assignments. Set reminders for renewals and re-assessments when projects change. Store certificates and supporting documents for audit readiness.

Review and adjust strategy: Conduct an annual review of A1 usage versus actual patterns. Flag recurring assignments that now warrant local employment or EOR. Monitor regulatory changes and update processes accordingly.

Country Examples Including A1 Certificate Germany and Other Key European Markets

A1 documentation requirements are triggered by physical work performed in the host country, meaning the compliance risk is driven by where the employee is physically present, not where the client is located or where the employer is headquartered.

Germany is a high-enforcement market for on-site documentation. A Polish or Dutch employer sending staff to Germany for an installation or consulting project needs A1 certificates proving continued home-country social security. German site inspectors commonly request A1 during checks. Germany may pair A1 checks with posting notifications and minimum wage compliance requirements., with fines up to €20,000 for failing to produce an A1 retroactively.

Belgium is a high-inspection jurisdiction for posted workers. Companies frequently need both social security evidence such as A1 coverage and separate host-country posting compliance documentation for site access and inspection readiness.

Nordic countries like Finland and Sweden have teams regularly crossing borders. A1 confirms home coverage for defined cross-border patterns, but local practices and portals vary.

Switzerland participates in European social security coordination for A1-style coverage despite not being an EU Member State, making it a frequent edge case for companies that assume EU-only rules.

The shared A1 framework comes with different national portals and enforcement styles. Don't assume one market's approach applies everywhere.

Strategic Next Steps on A1 Certificates for Mid-Market Companies in Europe

Ask yourself: Is our A1 usage systematic, documented, and aligned with how our people actually work? Do we know which roles and trips always require A1 and who owns the process? Are recurring assignments signalling a shift to EOR or local entities? Do we have audit-ready records and renewal tracking across all teams?

Your next moves should include consolidating data on cross-border work, current A1 usage, contractor relationships, and new-market plans. Then define the right mix: when to rely on A1 postings versus move to EOR or entities, balancing cost, compliance, and speed.

Choose a consolidated multi-model strategy when you simultaneously use contractors, A1 postings, EOR hires, and entity hires across Europe, because the compliance controls and evidence requirements differ materially by model.

For strategic clarity on A1 and cross-border employment decisions, talk to the experts at Teamed.

FAQs About A1 Certificates and Cross-Border Employment

How should companies handle A1 certificates for employees who regularly work in three or more countries?

Map all countries where work is performed and assess which system should apply under EU coordination rules. Complex multi-country patterns can exceed standard postings and require tailored advice from specialists who understand the coordination regulations.

Can digital nomads rely on an A1 certificate to stay under their home country social security system?

A1 is designed for structured, temporary postings, not open-ended remote living abroad. Long-term nomad arrangements often fall outside A1 and require different solutions.

How does the A1 certificate interact with contractor status and misclassification risk?

A1 generally applies to employees. If someone functions like an employee abroad without an A1, inspections may highlight misclassification risk.

At what point should a company stop relying on A1 certificates and consider local employment or an Employer of Record?

When work becomes permanent, recurring, or central to the business, or when headcount grows beyond a small project team, shift to local employment or EOR for sustainable compliance.

How often should mid-market companies review their A1 certificates and cross-border working patterns?

At least annually or on entering a new market. Adjust models proactively rather than after an inspection.

Do UK employers still use the A1 certificate after Brexit?

The UK uses EU-UK coordination agreements. UK employers often still need A1-style certificates for EU work. Check current guidance for each route.

What is mid-market?

Typically 200 to 2,000 employees or roughly £10m to £1bn in revenue. Large enough for complex cross-border issues, not yet operating like global enterprises.or