Social security agreements and secondments: the AHV in cross-border situations

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Whether a person who works across borders is covered by the Swiss old-age and survivors' insurance (AHV) depends first on Swiss domestic law, which attaches insurance to domicile and to the place of work. Where Switzerland has concluded an international agreement, that agreement decides which country's legislation applies and allows employees to be seconded for a limited period while remaining insured at home. This article explains the rules for the EU/EFTA area, the bilateral agreements, the special position of the agreements with China, India and South Korea, and the situation where no agreement exists. It closes with practical steps for groups that send staff to or from Switzerland.

The starting point: domicile and place of work

Under the Federal Act on Old-Age and Survivors' Insurance (OASIA; German: AHVG), everyone who is domiciled in Switzerland and everyone who works in Switzerland is compulsorily insured (Art. 1a para. 1 lit. a and b OASIA). Swiss law therefore follows a territorial approach, since it is the physical connection with Switzerland through residence or work, and neither the nationality of the person nor the seat of the employer, that triggers insurance. A foreign executive who takes up residence in Zug or Zurich, or who works there while keeping a home abroad, will in principle become subject to Swiss contributions from the first day; the contribution rates and the employer's duties are described in AHV contributions on salaries in 2026.

The Act contains a small number of exemptions. Persons enjoying diplomatic immunities are not insured, and neither are persons for whom insurance would create an unreasonable double burden (Art. 1a para. 2 lit. a and b OASIA). Self-employed persons and employees of employers without a Swiss establishment are also exempt as long as their work in Switzerland does not exceed three consecutive months per calendar year (Art. 1a para. 2 lit. c OASIA with Art. 2 of the Ordinance on Old-Age and Survivors' Insurance, OASIO; German: AHVV). Beyond these cases, domestic law alone would often lead to double coverage, which international agreements are designed to resolve.

EU and EFTA: coordination under the Free Movement Agreement

For relations with the member states of the European Union, Switzerland applies the EU social security coordination rules through Annex II to the Agreement on the Free Movement of Persons; for Iceland, Liechtenstein and Norway the corresponding rules apply through the EFTA Convention. These instruments determine a single applicable legislation for each person and coordinate benefits between the states concerned. An employee posted temporarily from one state to another can remain insured in the sending state for up to 24 months, provided that the posting is documented by an A1 certificate. Without that certificate, the host state is entitled to treat the employee as insured under its own law, which is why the A1 should be in place before the posting begins.

Bilateral social security agreements

Outside the EU/EFTA area, Switzerland has concluded bilateral social security agreements with the following states (AHV/IV information leaflet 890.e, as of 1 January 2026):

• Albania, Australia, Bosnia and Herzegovina, Brazil, Canada (with a separate agreement for Quebec), Chile
• China, India, Israel, Japan, Kosovo, Montenegro, North Macedonia
• Philippines, San Marino, Serbia, South Korea, Tunisia, Turkey
• United Kingdom, Uruguay, United States of America

Most of these agreements both determine the applicable legislation and coordinate benefits, and each fixes the maximum period for which an employee may be seconded while remaining insured in the sending state.

China, India and South Korea: applicable legislation only

The agreements with China, India and South Korea are of particular practical importance for readers of this site, and they are narrower than most others because they regulate only which state's contribution legislation applies. They contain no rules on the totalisation of insurance periods or on the coordination of pension benefits. Their main purpose is to avoid double contributions during secondments, and for that purpose they provide comparatively long posting periods of up to 72 months.

For a Chinese, Indian or Korean executive seconded to a Swiss subsidiary, this means that he or she can remain insured in the home country for the duration permitted by the agreement, provided that the secondment is properly certified, and that the Swiss entity will not owe AHV contributions on that salary during that period. Once the secondment ends or is converted into local employment, Swiss insurance applies in full. Any Swiss contribution years are then assessed under Swiss law alone: an old-age pension requires at least one full contribution year (Art. 29 para. 1 OASIA), and periods completed in China, India or South Korea are not counted towards it. Because the agreements do not coordinate benefits, foreign nationals from these states are subject to the domestic rule that pensions are paid only while the recipient is domiciled and habitually resident in Switzerland (Art. 18 para. 2 OASIA). On leaving Switzerland, nationals of these states may be able to claim a refund of contributions, subject to the conditions of the respective agreement; this is explained in Leaving Switzerland: AHV pensions abroad, refunds of contributions and voluntary insurance.

The same logic applies in the opposite direction. A Swiss employer sending staff to China, India or South Korea can keep them insured in Switzerland during the secondment period, whereas the home system of the host country would otherwise apply.

Maximum secondment periods

The maximum periods for which an employee may be seconded while remaining insured in the sending state are as follows:

Self-employed persons

Entrepreneurs who are self-employed in more than one country should note that several agreements contain a specific rule for them. Under the agreements with India, Canada/Quebec, the Philippines, South Korea and the USA, a self-employed person who is resident in one of the two states pays contributions only in that state. A Korean founder who lives in Switzerland and also carries on a business in Korea will therefore, in principle, be insured only in Switzerland for that activity. For self-employed persons from other states the domestic rules and the respective agreement must be examined separately; the Swiss contribution rules for the self-employed are set out in the article on AHV for the self-employed and for persons without gainful activity.

No agreement: Swiss insurance applies

Where Switzerland has no social security agreement with the home state, there is no secondment in the legal sense. An employee who works in Switzerland is insured under Art. 1a para. 1 OASIA from the start, irrespective of whether he or she remains insured in the home country, and the employer with a Swiss establishment must deduct and remit contributions. Double contributions can result, a cost factor that groups from states without an agreement should include in their planning.

For the outbound direction, Swiss law offers a partial remedy. Employees who work abroad for an employer based in Switzerland and are paid by it may remain insured in Switzerland, provided that the employer consents (Art. 1a para. 3 lit. a OASIA). This continuation of insurance avoids gaps in the Swiss contribution record, although it does not relieve the employee of any obligations under the law of the host state.

Practical checklist for groups

• Before any cross-border assignment, establish whether the home and host states are covered by the Free Movement Agreement, the EFTA Convention or a bilateral agreement, and which maximum posting period applies.
• Apply for the certificate of coverage (A1 for EU/EFTA postings) before the posting starts, and keep it available for the Swiss or foreign authorities.
• Diarise the end of the permitted posting period; from that date the host state's legislation normally applies.
• For employees from China, India or South Korea, explain at the outset that Swiss contribution years stand alone and that pensions and refunds follow separate rules.
• Where no agreement exists, budget for Swiss contributions from the first day and consider continued Swiss insurance for outbound staff under Art. 1a para. 3 lit. a OASIA.

How Ressos Legal helps

I advise foreign groups, executives and entrepreneurs on the social security aspects of secondments to and from Switzerland, including the choice of applicable legislation and the structuring of employment arrangements. I work alongside clients' home-country advisers so that the Swiss and foreign positions are aligned. Contact me to discuss a planned assignment.

Sources: Federal Act on Old-Age and Survivors' Insurance (SR 831.10) and Ordinance (SR 831.101), as of 1 January 2026; information leaflets of the AHV/IV Information Centre (ahv-iv.ch), as of 1 January 2026, in particular leaflet 890.e on social security agreements; Agreement on the Free Movement of Persons between Switzerland and the EU, Annex II; EFTA Convention; Swiss Compensation Office (zas.admin.ch). Figures as of October 2026.

For general information only. This article does not constitute legal or tax advice, does not replace advice on an individual case and creates no lawyer-client relationship. It reflects the legal position as of October 2026.