Anyone who marries in Switzerland and does not sign a prenuptial agreement automatically lives under the matrimonial property regime of participation in acquisitions (participation in acquired property). In Thailand, unless otherwise agreed, the system of Sin Suan Tua (personal property) and Sin Somros (marital property) applies. Both models pursue a similar goal: protecting pre-marital assets and fairly dividing what was acquired during the marriage, but the way they achieve this is a little different.
What Is the Same? The Basic Idea Behind Both Systems
In short:
- Assets owned before the marriage generally continue to belong to you.
- During the marriage, assets are shared depending on the type of asset – at the latest upon divorce or death.
Simplified Guidelines
| Switzerland (Participation in Acquisitions) | Thailand (Sin Suan Tua) | |
| Personal property | e.g. assets owned before the marriage, inheritances/gifts, personal items | e.g. assets owned before the marriage, inheritances/gifts if not designated as “joint”, personal items |
| “Marital property” | What is typically earned during the marriage, such as salary, income, etc., is treated as acquisitions | What is acquired during the marriage, including income, and often also “fruits” from personal property, such as interest or rental income |
| Division upon divorce | Basic principle: equalisation/division of the acquisitions | Basic principle: equal division of Sin Somros, 50/50 |
The Decisive Differences
A) Does it already belong to both during the marriage – or only at the end?
Switzerland: Many assets remain legally allocated to one person, or are deliberately purchased jointly. The “50/50 idea” mainly becomes relevant when the matrimonial property regime is dissolved, for example upon divorce or death. At that point, a calculation and equalisation takes place.
Thailand: Sin Somros is, in principle, joint marital property. This becomes particularly relevant in the management of assets and in important legal transactions.
Rule of thumb:
- Switzerland: “Separate in everyday life – equalisation at the end.”
- Thailand: “Marital property is more strongly understood as a joint category.”
B) Who may decide what? For example, selling real estate
Switzerland: In everyday life, each person can generally dispose of “their” own property. Restrictions may apply depending on the situation, for example in relation to the family home or jointly owned property.
Thailand: For important acts concerning Sin Somros, such as selling, mortgaging, or long-term leasing real estate, the express consent of both spouses is typically required.
Why this matters: If a property or major asset qualifies as Sin Somros, “signing alone” can quickly become a problem.
C) Burden of proof: who must prove whether something is “personal” or “marital”?
Switzerland: In case of doubt, assets are typically treated as acquisitions unless it can be proven that they are personal property, for example an inheritance or pre-marital asset.
Thailand: In Thailand as well, there is a strong presumption in favour of Sin Somros if the origin or timing of an asset is unclear. Anyone claiming that something is Sin Suan Tua must be able to prove it properly. Keyword: “traceability” – money flows and supporting documents.
Practical tip, valuable in both countries: Document the evidence: bank statements, gift agreements, inheritance documents, payment flows, and anything else showing where the money came from.
D) Real Estate & Binational Couples: The Classic Switzerland–Thailand Issue
One difference is less about the matrimonial property regime itself and more about reality, but it is highly relevant for couples:
In Thailand, land ownership by foreigners is heavily restricted. In practice, this often leads to property being registered in the name of the Thai spouse, even if the money partly or fully came from the foreign spouse. This is exactly where the burden of proof and the classification as Sin Somros become particularly sensitive, because the property may then potentially be treated as belonging to the person registered in the land register. At the same time, there are court cases under which provable personal capital contributions may, in certain circumstances, be reclaimed or reimbursed. Put simply: “whoever can prove that it was their money has better chances.” A joint real estate purchase always requires a clear arrangement.
E) Marriage contract / prenup: thailand has a strict “timing trap”
Switzerland: Marriage contracts are possible and can also be concluded later, provided the formal requirements are observed. It is possible to agree on complete separation of property or also on community of property. A Swiss marriage contract can be drafted very individually. In addition, a choice-of-law clause is possible.
Thailand: A prenuptial agreement is only effective if it is prepared before the marriage and officially registered at the time of marriage. “Submitting it later” does not work. Unlike in Switzerland, the options in a Thai prenuptial agreement are limited. In addition, one cannot simply choose foreign law in order to bypass Thai rules for assets located in Thailand.
If the couple married in Switzerland and lived in Switzerland for many years, a Swiss prenup makes sense. However, they must be aware that if they fully move to Thailand, meaning emigration and taking up residence in Thailand, the Swiss prenup may no longer have the same effect in Thailand. Therefore, alternative asset planning may be necessary in order to achieve an approximately similar result in the event of divorce.
How to remember it wasily
Switzerland – Participation in Acquisitions
Imagine that each person has their own account in everyday life. At the end of the marriage, an accounting is made: what was added during the marriage as “acquisitions” is equalised. Simplified: a 50/50 logic at the end.
Thailand – Sin Somros
Imagine that, in addition to personal property, there is a kind of “marital property pot”. What qualifies as Sin Somros is more strongly joint as a category – and for major decisions, both signatures are more likely to be required.
Conclusion for Swiss-Thai Couples
Sin Somros and participation in acquisitions pursue a similar fairness objective, but the rules in everyday life and the risks in case of dispute differ.
If you as a couple have connections to Thailand or are moving there completely, these four points are particularly important:
- Documentation: Evidence, money flows, and origin of funds should be documented. Otherwise, in case of doubt, assets may be treated as “marital”.
- Joint decision-making for major assets in Thailand: You cannot simply assume that one signature is enough.
- Prenuptial agreement in Thailand: If at all, then before the marriage and correctly registered, otherwise it is worthless. A Swiss marriage contract will not automatically be valid. The consequences should be reviewed before moving. Divorce may still be possible in Switzerland with a jurisdiction clause, but enforcement in Thailand can lead to considerable problems.
- Forward-looking planning: For larger financial amounts, planning should be done in advance and both divorce and inheritance scenarios should be taken into account.
FAQ
Does Sin Somros apply automatically in Thailand?
Yes, if there is no valid prenuptial agreement, the Thai system works with Sin Suan Tua and Sin Somros.
Is divorce in Thailand always 50/50?
Sin Somros is generally divided equally, simply put.
Can I also conclude a prenuptial agreement in Thailand after the marriage?
Not in this form. Its validity depends on “before the marriage” plus registration at the time of marriage.
