Marrying a Thai: why prenuptial agreements are not a luxury

Getting married in Thailand often feels like the culmination of a long journey. You have found each other, the paperwork is in order, and the amphur is ready. What many couples do not realize: from the moment the signature appears on the Thai marriage register, a complete property law system applies that you never chose.

And that system can hit you hard. Whether you have built up assets in the Netherlands, run your own small business, or have plans to buy a house together in Isaan. Anyone who has something to protect would do well not to leave this to chance.

What the Thai standard system entails

The Thai Civil and Commercial Code recognizes two categories of property. Sin suan tua is your personal property: everything you owned before the marriage, and everything you inherit or receive as a gift during the marriage. Sin somros is joint property: income, purchases made during the marriage, investment returns, and even rental income from a personal home. In the event of a divorce, sin somros is divided 50/50, even if everything is in the name of one partner.

The burden of proof is a catch. Anyone wishing to designate something as personal must be able to demonstrate this with bank statements, receipts, or proof of purchase. If the judge has doubts, he rules that it is joint property. In the Netherlands, a limited community of property has been the standard since 2018; in Belgium, the community of acquisitions. Three countries, three systems, and as soon as you marry internationally, they intersect.

Which law actually applies to your marriage?

A persistent misconception: the country where you marry or the nationality of the partners supposedly automatically determines the applicable law. That is incorrect. For marriages entered into from 29 January 2019 onwards, the Matrimonial Property Regime Regulation applies within the EU, in which both the Netherlands and Belgium participate. The general rule: without a choice of law, the law of the first common domicile after the marriage applies.

In concrete terms: if you marry in Bangkok and continue to live there, you are in principle subject to Thai law. If you move together to the Netherlands or Belgium, you often become subject to that law. If you move back later, the original law continues to apply; there is no longer any automatic adjustment. For marriages between September 1, 1992, and January 29, 2019, the old Hague Convention on Matrimonial Property Regimes of 1978 still applies, with different connecting factors. Anyone who does not make any provisions regarding this leaves the outcome to a judge.

How a Thai marriage contract works

Thailand has the sanya kon somros, loosely translated as: contract for marriage. The rules are set out in Articles 1465 to 1469 of the Civil and Commercial Code. For it to be valid, you must strictly meet four requirements:

• The contract must be drawn up in writing; verbal agreements do not count.
• Both partners and two witnesses aged at least 20 must sign.
• The content must not be contrary to public order or morality, and must not declare foreign law applicable to Thai assets.
• The contract must be registered at the amphur at the same time as the marriage registration. Not before, not after, exactly on the same day.

The latter is tough. The Thai Supreme Court confirmed in ruling 3346/2532 that a contract that is not correctly co-registered is automatically void. In that case, you fall back on the standard system.

What a Thai contract cannot regulate

Thai prenuptial agreements are legally more limited than many people think. What is possible, however, is to specify which assets are personal, agree on management rules for joint assets, and determine who may independently access which accounts or shares.

What is not permitted: overriding the statutory 50/50 division, contracting away alimony, disinheriting a spouse or child, or declaring foreign law applicable. If you attempt to do so anyway, the court will declare the clause void. The Supreme Court has repeatedly confirmed this, including in judgments 1428/1982, 2159/2562, and 195/2564. A Thai marriage contract is therefore not a Dutch separation of property. It primarily refines classification and administration; it does not lock everything down.

The land ownership problem

For many Dutch and Belgian men, in practice, it revolves around land and houses. Foreigners are not allowed to own land in Thailand. Since a ministerial regulation of March 23, 1999, a Thai woman married to a foreigner may purchase land, but only if she and her husband declare that it is her personal property, purchased with her own money.

In practice: the man deposits the money, the woman buys land, and the man signs a declaration stating that he has no rights. Many men believe that this leaves them with no legal recourse. However, in 2022, the Thai Supreme Court made an important ruling (judgment 1523/2565). A foreigner proved that he had paid four million baht of his own money for a house in his wife's name. The judge ruled that the Land Office declaration is a ministerial regulation that cannot override the Civil Code. The man did not receive ownership, but he did receive a refund of his deposit. Proof is therefore decisive.

Changes during the marriage

This is where the conflict lies between the systems. Under Dutch law, you can amend your conditions during the marriage via a notary, since 2012 even without judicial approval. In Belgium, an amendment deed at the notary handles this.

In Thailand, it is stricter. According to Article 1467, a marriage contract can only be amended after registration with the approval of the court. Even worse: agreements spouses make during the marriage regarding their assets, a so-called post-nup, can be unilaterally voided by either partner within one year after the divorce, pursuant to Article 1469. For those seeking certainty, they are therefore virtually worthless. So, arrange it before the marriage, not afterwards.

Costs and the practical route

Ideally, you should have a Thai marriage contract drawn up by a Thai lawyer, preferably bilingual, six to eight weeks before the wedding date. Expect to pay tens of thousands of baht for quality work. A Dutch notary charges an average of between 800 and 1600 euros for prenuptial agreements, with outliers exceeding 2000 euros. In Belgium, the price is generally between 400 and 1500 euros, plus approximately 100 to 200 euros for registration in the Central Register of Marriage Contracts.

The workable sequence for anyone who has something to protect:

• Decide together what you want to arrange: only separation of assets, or also management, business, inheritance, and pension.
• Make an appointment with a notary in the Netherlands or Belgium well before the wedding date; allow two to three months for processing.
• Include a choice of law clause for Dutch or Belgian law.
• Have a Thai lawyer draft a supplementary Thai prenuptial agreement for your Thai assets, consistent with the European contract.
• Keep physical and digital copies of all supporting documents for financial flows, donations, and purchases.
• Register the Thai marriage with your municipality in the Netherlands (mandatory for residents) or via your municipality or the consular post in Bangkok.

Common mistakes and what not to forget

The biggest mistake is thinking that a Thai marriage automatically falls under Dutch or Belgian law simply because you both have European income or a house in Eindhoven. Without a choice of law, the law of your first common place of residence decides. A second mistake: waiting until after the marriage to arrange something. In Thailand, this can only be done through the court, and a post-nuptial agreement can be unilaterally annulled.

Do not rely blindly on the Land Office declaration either. Without proof of payment, it is a disadvantageous document for you, and for your wife, it is not an inviolable protection. And do not forget the will: under Thai inheritance law, spouses and children have a statutory minimum share that you cannot remove through a prenuptial agreement. For your Dutch or Belgian assets, you need a will that is valid in both jurisdictions. The same applies to pension equalization, which in the Netherlands automatically sends half of the old-age pension accrued during the marriage to your ex, unless you contract this away.

Ready to see how Snowflake works?

A Thai-Dutch or Thai-Belgian marriage without a prenuptial agreement is a gamble with an unknown outcome. Arrange this before the marriage in the Netherlands or Belgium, with an explicit choice of law, and have a Thai lawyer draft a supplementary contract for your Thai assets. Keep every piece of evidence. Good advice pays for itself handsomely within a single conflict.

Sources: Thai Civil and Commercial Code (Articles 1465-1469, 1471-1474, 1476, 1533-1535), Regulation (EU) 2016/1103, Hague Convention on Matrimonial Property Regimes 1978, Belgian Private International Law Code, Book 10 of the Dutch Civil Code, Netherlands Worldwide, Thai Supreme Court judgments 3346/2532, 1428/1982, 2159/2562, 195/2564 and 1523/2565, AIM Bangkok, Siam Legal, Thailand Law Online, Notaris.nl, Notaris.be, LawBase, Wikifin, The Hague Institute for Legal Research, Vreemdelingenrecht.be, Thailandblog.nl.

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