The A1 Form – Certificate of Coverage Explained

A complete compliance guide to the A1 Form (also known as the A1 certificate). Learn what the A1 form is; who needs it; what the rules are; and how to get one.

13 January 2026 | By Alex Schulte

Cross-border work in Europe has become routine. Regional managers hop between offices in three countries. Sales teams attend conferences in Vienna, then client meetings in Brussels. The A1 Certificate – formally known as the Portable Document A1 or Certificate of Coverage – is what makes it work.

For global mobility managers navigating Europe’s 27 distinct social security systems, the A1 form (otherwise known as the A1 certificate) is the single most important document separating legal compliance from administrative chaos and financial penalties.

In 2026, the A1 has evolved far beyond its paper origins. Digital wallets, real-time verification systems, and landmark court rulings have transformed how the certificate functions. Brexit has added new complexity for UK-EU movements. And the rise of hybrid work has forced a complete rethink of when and how A1s apply.

In this guide, we’ll explain what the A1 actually does, when you need one, how to get one, and what happens if you don’t.

Whether you’re managing a single posting to Germany or coordinating a workforce scattered across the EEA, this is your roadmap to A1 compliance in 2026.

What is an A1 form?

The A1 form is a legal determination made by EU social security authorities that confirms that your employee remains insured in their home country while working temporarily in another European state.

Without an A1, the default rule is simple and brutal: work in France, pay French social security. Work in Germany, pay German social security. From the first hour of work. Even if you’re only attending a meeting.

The A1 overrides this default. It tells the host country’s authorities: “This worker is already covered. You have no jurisdiction to collect contributions for the period specified on this certificate.”

What the A1 covers

The A1 certifies coverage across all major branches of social security:

• Sickness and maternity: Healthcare access, medical leave, parental benefits
• Old-age and survivors: Pension contribution history and dependent rights
• Invalidity: Long-term disability and loss of earning capacity
• Accidents at work: Occupational injuries and diseases during the assignment
• Unemployment: Accumulation of periods for future unemployment claims
• Family benefits: Child benefits and family-related social supports

This comprehensive coverage is why the A1 matters for employers’ duty of care. It ensures your employee isn’t suddenly uninsured for a workplace accident just because they’re working in another country.

When you need an A1 form

The A1 requirement is triggered by cross-border work. But “cross-border work” covers far more situations than most organisations realise.

Scenario 1: Posted Workers (Article 12)

This is the classic A1 scenario: your company sends an employee from their home country to work temporarily in another Member State, becoming what’s known as a posted worker.

Under Article 12 of Regulation 883/2004, the employee can remain in their home country’s social security system if four conditions are met:

Article 12 posting requirements

• Duration limit: The anticipated duration of the work must not exceed 24 months. If it is known from the outset that the assignment will last longer, the home country cannot issue an A1 under Article 12.
• Direct relationship: A “direct relationship” between the employee and the posting employer must be maintained throughout the assignment. This means the employer must retain the authority to determine the nature of the work, the right to dismiss the employee, and the obligation to pay the salary.
• No replacement rule: The worker cannot be sent to replace another posted person whose posting period has ended. This prevents organisations from circumventing local social security obligations by rotating staff through the same role indefinitely.
• Substantial home activity: The posting employer must normally carry out “substantial activities” in the state where it is based. This is verified by looking at turnover, payroll size, and the number of contracts performed in the home country versus the host country.

Self-employed postings: Self-employed individuals can obtain an A1 for up to 24 months under Article 12(2), provided they’ve been pursuing their activity in the home country for at least two months before the move.

Scenario 2: Multi-state workers (Article 13)

Regional managers, airline crew, or hybrid workers splitting time between home and headquarters. These are multi-state workers, employees who regularly work in two or more Member States without a single fixed location.

For these workers, Article 13 determines which country’s social security system applies.

The key question: Does the worker perform a “substantial part” of their activity in their state of residence?

“Substantial” means at least 25% of the worker’s activity, measured by working time or remuneration.

Multi-state worker decision tree

Two landmark rulings from the Court of Justice of the European Union in 2025 have fundamentally clarified how the 25% threshold works:

• During GKV-Spitzenverband (Case C-743/23, December 11, 2025), the court ruled that when calculating the 25% threshold, you must include all professional activities, including work performed in third countries outside the EEA and Switzerland.
• Hakamp (Case C-203/24, 2025) confirmed that the 25% calculation must be based strictly on working time and/or remuneration. National authorities cannot use other “indicative” factors, like where the employer is managed or vessel registration.

Special categories: aircrew, mariners, and civil servants

Specific rules apply to transport and public sector workers, reflecting their unique operational profiles:

• Aircrew: Since 2012, social security legislation for flight and cabin crew has been determined by their “Home Base”, the location where the crew member normally starts and ends a duty period and where the operator is not responsible for accommodation.
• Mariners: Seafarers are generally subject to the legislation of the state whose flag the vessel flies. Exception: If the mariner resides in the same Member State where their employer is registered, the legislation of the residence/employer state takes precedence over the flag state.

Scenario 3: remote workers

Since the 2023 Multilateral Framework Agreement, remote workers can perform between 25% and 49.99% of their working time in their state of residence while remaining subject to the social security legislation of the state where their employer is established.

These are the requirements:

• Both the residence state and the employer’s state must be signatories to the agreement
• Employee must have only one employer (or multiple employers in the same state)
• Telework must be performed using IT connectivity that keeps the worker connected to the employer’s environment
• Both employer and employee must consent to the derogation

Applications are valid for a maximum of three years and can be renewed. The application must be filed in the state whose law applies (the employer’s state).

Scenario 4: business travel (the “first hour” rule)

Here’s where many organisations get caught: under EU law, there is no minimum duration for an A1 requirement. A certificate is legally required from the very first hour an employee performs work in another Member State.

This includes:

• Attending a client meeting
• Participating in a training session
• Visiting a trade fair or exhibition
• Working from a hotel room while on a personal vacation

The “workation” phenomenon has created a massive compliance gap. An employee spending two weeks in Portugal while continuing to work remotely for their German employer technically needs an A1 certificate for those two weeks.

The post-Brexit reality: UK-EU social security coordination

Brexit created three separate frameworks for UK-EU movements:

1. Withdrawal Agreement: Protects pre-2021 cross-border situations under full Regulation 883/2004 rules.
2. TCA protocol: Governs new moves from January 1, 2021, with 24-month posting limits.
3. UK-EFTA conventions: Separate agreements with Switzerland and EEA EFTA states.

The critical Article 16 gap: To extend the TCA Protocol beyond 24 months, employers must register in the Host Country from day one of the extension (with significant cost implications in high-contribution jurisdictions like France.

The 2026 UK-EU reset

The Labour government and the EU are conducting the first TCA review in 2026. While not a full renegotiation, improvements to worker mobility and A1 processes are under discussion through the Specialised Committee on Social Security Coordination.

How to obtain an A1 certificate

The responsibility for obtaining an A1 certificate lies with the employer. Applications must be submitted before the assignment begins. While some authorities allow retroactive applications, enforcement is increasingly focused on prior notification.

Processing realities and the “proof of application” strategy

Processing times vary wildly by country. Automated portals in the Netherlands and Germany can issue certificates in days. HMRC in the UK has historically taken several months.

Enforcement, penalties, and the cost of non-compliance

A1 enforcement has moved beyond traditional high-risk sectors. White-collar professionals on short business trips, conference attendees, and remote “workationers” are all subject to inspection.

The double contribution nightmare

Beyond financial penalties, the absence of an A1 can trigger double contribution exposure. If an employee is audited without an A1, the host country may demand immediate payment of local social security contributions.

These contributions are rarely recoverable. Worse, they don’t exempt the employer from the ongoing obligation to pay contributions in the home country until an A1 is eventually issued and backdated.

A1 and shadow payroll

For a global mobility program to function effectively, A1 processing must be tightly integrated with shadow payroll, a parallel payroll process used to report an expatriate’s compensation in the host country for tax and social security compliance, without actually paying the employee a second time.

The A1 form provides the legal justification for “shadowing” only the tax, not the social security, in the host country.

Digital transformation: the 2026-2027 horizon

The A1 certificate is undergoing a massive digital transformation aimed at making social security coordination faster, more secure, and less bureaucratic.

EESSI: the electronic backbone

The Electronic Exchange of Social Security Information (EESSI) is now the standard back-end system connecting thousands of national social security institutions across Europe.

In 2025, the European Labour Authority (ELA) launched the PROGRESS portal, a secure platform allowing national administrations to map their EESSI setups and test interoperability for new system releases.

By early 2027, a new EESSI Data Model will be deployed, further streamlining the exchange of complex multi-state worker data.

ESSPASS: the digital wallet revolution

The most significant change for mobility managers is the European Social Security Pass (ESSPASS) project. Currently in final pilot phases (2023-2025), ESSPASS aims to allow workers to store their A1 certificates and European Health Insurance Cards (EHIC) in a digital wallet on their smartphones.

This digital pass can be instantly verified in real-time by labour inspectors or healthcare providers using the European Digital Identity (EUDI) framework.

For global mobility managers, this means investing now in digital infrastructure that can integrate with these emerging systems.

Common A1 compliance mistakes (and how to avoid them)

❌ Mistake 1: assuming short trips don’t require an A1

There is no minimum duration threshold. Work performed from the first hour triggers the requirement. So, implement a travel pre-approval system that automatically flags all cross-border business travel for A1 assessment.

❌ Mistake 2: relying on the 24-month limit for UK-EU postings

The A1 must be obtained before work begins. If you apply after the employee has already started working in the host country, you risk dual contribution exposure for the period before the certificate is issued. Build A1 application processing time (typically 2-8 weeks) into your assignment planning timeline.

❌ Mistake 3: ignoring third-country activity in 25% calculations

The 2025 GKV-Spitzenverband ruling confirms that all professional activities, including third-country work, must be included in the calculation. Therefore, update your tracking systems to capture all working time globally, not just within the EEA.

❌ Mistake 4: allowing extensions without a new A1

The moment the original A1 expires, the employee must be registered in the host country’s social security system. There is no grace period. Set automated alerts for A1 expiry dates at least 90 days beforehand. If an extension is likely, initiate the new A1 application immediately.

❌ Mistake 5: treating telework as exempt

Cross-border telework is subject to the same coordination rules as physical presence. Without proper A1 coverage under the Telework Framework Agreement, the employee may be subject to social security in their residence state. Implement a “work location declaration” process that requires employees to disclose their physical work location, not just their employer.

Centuro Global removes the complexity

The A1 Certificate is the linchpin of compliant cross-border work in Europe. But managing A1 compliance at scale, from tracking travel patterns and calculating 25% thresholds with third-country activity to monitoring expiry dates, and navigating six different national portals, overwhelms manual processes the moment your workforce becomes truly mobile.

Centuro Global’s Travel Compliance Assistant eliminates this burden through intelligent automation. Our AI-enabled platform identifies A1 requirements in real-time, automatically calculating multi-state worker thresholds and tracks certificate validity across your entire workforce.

When the three-day Vienna conference triggers an alert before your employee boards the plane, A1 compliance transforms from an administrative nightmare into a strategic enabler of European talent mobility.

Try it now – book a demo.