International Employment Contract: Secondment vs Expatriation

Sending an employee to work abroad may seem straightforward in theory. In reality, the choice between secondment and expatriation carries profound consequences for the employment contract, social contributions, personal taxation, and employer liability. Confusion between these two regimes can expose the company to URSSAF assessments, double taxation, and costly labor court disputes. In 2026, with strengthened cross-border controls within the European Union and the generalization of the directive on the posting of workers (2018/957/EU), mastering these distinctions has become an absolute priority for HR and legal departments. This article compares point by point the two statuses, their social security regime, their tax treatment, and the essential contractual precautions.

Secondment and expatriation: definitions and legal foundations

Before analyzing the differences, precise definitions must be established, as the boundary between the two regimes is regularly misunderstood in companies.

Secondment: a maintained link with the system of origin

International secondment is the situation in which an employer temporarily sends an employee to perform their activity in another country, while maintaining their original employment contract with the sending company. The seconded employee retains their affiliation with the social security scheme of their country of origin, provided they comply with the conditions set forth in the applicable European regulations or bilateral conventions.

Under European law, regulation (EC) No. 883/2004 on the coordination of social security systems provides that a seconded employee remains affiliated with the social security scheme of the sending State for a maximum period of 24 months, provided that:

• the foreseeable duration of the secondment does not exceed 24 months;

• the employee is not sent to replace another seconded person;

• the employer carries on a substantial activity in the sending State (the so-called "substantial activity" criterion).

This affiliation is materialized by the A1 form (or E101 for certain third States), issued by the social security body of the country of origin. This document is essential: without it, the employee may be charged contributions in the country of reception, generating a double contribution.

From an employment law perspective, directive 96/71/EC, as amended by directive 2018/957/EU, imposes on the seconded employee a core of mandatory rights from the country of reception: minimum wage, maximum working time, statutory paid leave, health and safety rules. Since July 30, 2020, if the secondment exceeds 12 months (renewable to 18 months upon justification), the entire set of employment conditions in the country of reception becomes applicable, except for rules on the establishment and transferability of supplementary pensions.

Expatriation: a break with the system of origin

Expatriation is based on opposite logic. The expatriate employee is hired locally or offered an expatriation contract that suspends or terminates their original employment contract. They leave the French social security scheme and join that of the country of reception. In France, the employer may nevertheless opt, with the employee's agreement, for a voluntary continuation under the general scheme through the Caisse des Français de l'Étranger (CFE), subject to specific contributions.

Unlike secondment, no maximum duration is imposed on expatriation. The situation is designed to be ongoing, often lasting several years. The expatriate employee is subject to local social legislation in its entirety, which requires a thorough analysis of the employment law of the country of reception, particularly regarding dismissal, end-of-service compensation, and union representation.

Social security regime: practical differences

Secondment: portability of social rights

The main advantage of secondment lies in the portability of social rights: the employee continues to accumulate pension rights in their original scheme, benefits from their usual health coverage (via the European health insurance card in the EU), and contributes to ARRCO/AGIRC supplementary schemes if they are French.

For countries outside the EU, France has concluded more than 40 bilateral social security conventions (with the United States, Canada, Japan, Brazil, etc.) that organize similar mechanisms. In the absence of a convention, the risk of double contribution is real: the employee and employer can be liable in both States simultaneously.

Expatriation: local affiliation and protection to be rebuilt

In expatriation, the employee joins the local scheme, which means that their future rights depend on the generosity and stability of the foreign system. For destinations with weak social protection, membership in the CFE and supplementary private insurance (medical coverage, income protection) becomes essential. This additional cost can represent 10 to 20% of the total cost of mobility depending on the countries.

The administrative management of expatriation is also heavier: the employer must ensure compliance with registration obligations with local social authorities, on pain of sometimes significant penalties. For HR teams managing multiple mobilities simultaneously, tools dedicated to the management of international employment contracts allow centralization of documents and securing each step of the process.

Taxation: tax residence, conventions, and income taxation

The determining criterion of tax residence

In tax matters, the central concept is tax residence. Under French law, Article 4 B of the General Tax Code (CGI) considers as tax residents in France those persons who have their principal residence or main place of stay in France, whose principal professional activity is carried on in France, or who have the center of their economic interests in France.

An employee seconded for fewer than 183 days per year in a foreign country generally retains their tax residence in France and remains liable there on all worldwide income (subject to bilateral tax conventions). Conversely, an expatriate who genuinely transfers their residence to the country of reception may lose their French tax residence, which has major consequences: they are no longer subject to taxation in France except on income of French source.

Bilateral tax conventions: tool against double taxation

France has signed more than 130 tax conventions designed to prevent double taxation. These conventions generally follow the OECD model and allocate the right to tax employment income to the State where the activity is carried on, unless the employee is tax resident in the other State, does not stay there more than 183 days, and is paid by a non-resident employer.

For short secondments (less than 183 days), the convention often maintains taxation in France. For long-term expatriates, it transfers taxation to the country of reception. But some conventions include specific provisions for pension schemes, stock options, or passive income that complicate the analysis.

Practical implication for the employer: assignment letter and remuneration package

In practice, the employer must carefully structure the international remuneration package: maintenance of base salary, expatriation allowance (often 10 to 15% of gross salary), housing costs, children's schooling, annual return ticket. Each element has different tax treatment depending on whether it constitutes a reimbursement of professional expenses or a taxable benefit in kind.

The management of these complex contractual documents — amendments to the contract, assignment letters, mobility policies — benefits from being digitized and secured. For HR teams managing multiple mobilities, the electronic signature solution for HR by Certyneo allows these documents to be signed remotely, with probative value equivalent to a handwritten signature.

Contractual obligations and administrative formalities

The secondment contract: content and precautions

The secondment contract or amendment must mandatorily mention, in accordance with directive 2019/1152/EU on transparent and predictable working conditions:

• the foreseeable duration of the secondment;

• the currency in which remuneration is paid;

• cash or non-cash benefits related to the secondment;

• the conditions for repatriation;

• the applicable law (generally the law of the original contract, supplemented by the mandatory core of the country of reception).

It is strongly advised to add a repatriation clause specifying the modalities of return in case of illness, accident, or early termination of the secondment, as well as a choice of law clause under regulation (EC) No. 593/2008 (Rome I).

The expatriation contract: structure and vigilance points

The expatriation contract can take two forms:

• Amendment to the existing employment contract, which suspends the original contract and specifies the conditions for return to France;

• Local contract concluded directly with a foreign subsidiary, which then terminates the French contract (risky option as it deprives the employee of their acquired rights in France).

The first form is the most protective for the employee and the least risky for the company. It must explicitly provide: the maintenance or not of acquired benefits (seniority, classification), the conditions for reintegration at the end of the expatriation, and the fate of the contract in case of disappearance of the foreign subsidiary.

In all cases, the legal value of electronic signature on these documents is fully recognized under European law, which facilitates the conclusion of cross-border acts without physical displacement.

Unavoidable administrative formalities

Beyond the contract, several formalities are mandatory:

• A1 form for secondees in the EU/EEA/Switzerland: to be requested from URSSAF before departure;

• Advance declaration of secondment in the country of reception (mandatory in all Member States since directive 2014/67/EU);

• Designation of a representative of the company in the country of reception (mandatory in many States, including France for foreign companies);

• Registration with local tax authorities if the duration exceeds the thresholds of the applicable convention.

All of these documents benefit from being archived electronically and securely. The dematerialized payslip and archiving of contracts with timestamping constitute proof that can be invoked in case of control by French or foreign authorities. To learn more about the probative value of electronic timestamping of documents, the guide on electronic timestamping by Certyneo details the applicable certification levels.

Comparative summary table: secondment vs expatriation

This summary table confirms that there is no universally preferable regime: the choice must result from case-by-case analysis taking into account the foreseeable duration, the country of reception, the employee's tax profile, and the company's strategic objectives. HR teams can rely on the AI-powered contract generator from Certyneo to produce draft amendments compliant with the requirements of each regime, then to be validated by specialized counsel.

Legal framework applicable to international mobilities

The management of international mobilities is part of a complex body of European, international, and national standards that must be mastered to avoid any risk of non-compliance.

European Union law

The Regulation (EC) No 883/2004 of the European Parliament and of the Council, supplemented by its implementing regulation (EC) No 987/2009, forms the cornerstone of the coordination of social security systems within the EU, the EEA, and Switzerland. It establishes the principle of a single applicable legislation and sets out the arrangements for posting (Article 12) and multi-state situations (Article 13).

The directive 96/71/EC on the posting of workers, substantially revised by directive 2018/957/EU (transposed into French law by ordinance No. 2019-116 of February 20, 2019), defines the minimum rights applicable to employees posted in the EU: remuneration, working time, accommodation conditions, and the hard core of collective agreements.

Directive 2019/1152/EU on transparent and predictable working conditions imposes new standards for contractual information, particularly for mobile workers (Articles 7 to 9).

Regulation (EC) No. 593/2008, known as "Rome I," governs the law applicable to contractual obligations, allowing the parties to choose the law applicable to the international employment contract, provided that it does not deprive the employee of the mandatory provisions of the objectively applicable law.

International tax law

Bilateral tax conventions predominantly follow the OECD model (2017 version, updated in 2024). Article 15 of the OECD model governs the taxation of employment income. In France, Article 4 B of the General Tax Code determines tax residence, and Article 81 A of the CGI provides for an exemption from income tax for certain employees posted abroad under strict conditions (duration of stay abroad exceeding 120 or 183 days depending on the activity).

French employment law

Articles L. 1261-1 to L. 1266-1 of the Labor Code transpose the posting directive into French law. They notably provide for the obligation of advance declaration for foreign employers posting employees in France and the criminal and administrative penalties applicable in case of failure to comply (fine up to €500,000).

Security of documents and digital documentation

The electronic signature of international mobility contracts is governed by eIDAS regulation No. 910/2014 (currently being revised under eIDAS 2.0), which confers full legal value on advanced and qualified electronic signatures. The GDPR No. 2016/679 applies to the processing of personal data of employees in the context of mobility procedures, particularly for data transfers outside the EU to third countries (Articles 44 to 49).

Illustrative use-case scenarios: international mobility

Scenario 1 — A mid-sized industrial company managing frequent intra-European secondments

These scenarios are illustrative: they describe typical situations and do not report any measured results from a client. A mid-sized company in the industrial sector, with approximately 1,200 employees and subsidiaries in five EU member states, carries out numerous short- and medium-term postings each year for assembly, maintenance, and technical training assignments. When HR teams manage all A1 forms, posting amendments, and prior declarations on paper, processing times per file quickly increase.

With an integrated electronic management and signature solution, processing time per file and data entry errors can decrease significantly. Timestamped archiving of signed A1 forms and amendments makes it possible to respond quickly to a labor inspection check in a host country. The return on investment remains to be measured on your own scope, before and after a pilot.

Scenario 2 — A professional services group managing long-term expatriations outside the EU

A consulting and engineering group of approximately 3,500 employees sends around fifteen senior executives abroad each year on long-term expatriate assignments (3 to 5 years) to countries in Southeast Asia and sub-Saharan Africa, regions with limited coverage under bilateral social security agreements. The complexity of each file — expatriation contract, French contract suspension amendment, CFE enrollment, assignment letter, international compensation policy — represents a significant administrative workload per file.

A digital platform centralizing the production, signature, and archiving of documents makes it possible to reduce the administrative workload and limit incidents related to unsigned or misplaced contract versions. The ability for employees to sign their documents from their future country of assignment, without physically returning to France, improves the candidate's mobility experience. The scale of the gain is to be measured on the actual scope, before and after a pilot.

Scenario 3 — A hypergrowth tech start-up recruiting its first employees abroad

A French SaaS start-up that recently completed a Series B funding round is hiring three employees in the United Kingdom and Germany for the first time, while also considering the temporary posting of two French engineers to Berlin for a start-up phase lasting a few months. The HR team, made up of a single person, has no prior experience with international mobility.

By relying on a contract generator adapted to posting and expatriation regimes, combined with an eIDAS-compliant electronic signature solution, the start-up can quickly produce and have signed posting amendments compliant with directive 2018/957/EU. A1 forms must be obtained from URSSAF before the engineers' departure, in order to avoid any risk of double affiliation. Automating the first levels of document compliance can reduce reliance on legal fees, while still retaining the validation of a specialized advisor for complex tax matters. The actual savings are to be measured on the start-up's own scope, before and after a pilot.

Frequently Asked Questions

What is the maximum duration of an international assignment before it becomes expatriation?

Under European law, Regulation (EC) No. 883/2004 sets 24 months as the period during which an assigned employee may remain affiliated with the social security scheme of their home country. Beyond this period, affiliation with the host country's scheme becomes mandatory, which practically brings the situation closer to expatriation. Outside the European Union, bilateral conventions establish their own thresholds, which vary depending on the state.

Can an assigned employee be subject to the labor law of the host country?

Yes, partially from day one. Directive 2018/957/EU requires the immediate application of a core of mandatory rights in the host country: legal minimum wage, maximum working hours, paid leave, and safety rules. If the assignment exceeds 12 months—extendable to 18 months upon justification—all local employment conditions apply, with the exception of rules relating to the establishment and portability of supplementary pensions.

What is the purpose of Form A1 in the context of an assignment in Europe?

Form A1 is issued by the social security body of the home country. It certifies that the employee remains affiliated with their original scheme during the assignment period, which prevents double contributions in both states. Without this document, the authorities of the host country may require payment of local contributions. The employer must request it before the employee's departure, not after the assignment begins.

What are the tax consequences of expatriation for the employee?

Expatriation generally results in a transfer of tax residence to the host country, which changes which state is authorized to tax the employee's worldwide income. France applies its own criteria to determine tax residence—habitual home, principal activity, center of economic interests—independently of the parties' wishes. Bilateral tax conventions may prevent double taxation, but their application requires a case-by-case analysis depending on the country involved.

Can an expatriate employee be maintained in the French social security scheme?

Yes, subject to conditions. The employer and employee may opt for voluntary membership in the Fund for French Citizens Abroad, which preserves comparable health, maternity, and basic retirement coverage to the general scheme. This option generates specific contributions payable by both parties and does not waive the need to analyze the local social security obligations of the host country, which may require parallel affiliation depending on its national legislation.

Conclusion

Secondment and expatriation are two fundamentally distinct regimes with profound consequences for employment contracts, social security, and the taxation of both employee and employer. Secondment offers the portability of social rights and valuable contractual continuity, but imposes a limited duration and compliance with the mandatory core of the country of reception. Expatriation offers greater flexibility in duration, but requires a complete reconstruction of social protection and a thorough tax analysis.

In both cases, the quality of contractual documentation — amendments, assignment letters, A1 forms, advance declarations — is decisive for the compliance and legal security of the mobility. Certyneo allows you to produce, have signed, and archive these documents remotely, with full legal value, regardless of the employee's location.

Discover how Certyneo secures your international mobilities or estimate your return on investment today.