Jointly owned marital and personal property and real estate under Thai family laws
The Thai marriage property regime is largely covered by the section property between husband and wife in the Civil and Commercial Code. In general 'benefit and income' of each spouse acquired during marriage will under Thai law become jointly owned 'marital property' between husband and wife.
A prenuptial agreement is an allowed concept in Thailand however it is not possible to exclude the general property regime between husband and wife in a prenuptial agreement.
Thai law specifies that property belonging to either spouse before the marriage remains his or her personal property during the marriage. If during the marriage personal property has been exchanged to other property this remains a personal property (Sin Suan Tua).
In case land is bought in Thailand the land must be a personal property of the Thai spouse and it will be managed by the Thai spouse.
In general property acquired during marriage (subject to the above section 1472) and 'fruits' from personal property during marriage will become jointly owned property (Sin Somros) between husband and wife. Property acquired by inheritance, legacy or gift shall become personal property, unless stated differently in the will.
If you have 100,000 Thai baht in your bank account at the time of marriage and at the time of divorce in Thailand you saved an additional 15,000 baht from your income and received 5,000 interest over your savings your spouse shall according to Thai law be entitled to half of the increase (i.e. 10,000 baht). An inheritance will in principle not a marital property but a personal property (Sin Suan Tua) of the person receiving the inheritance and the other spouse is not entitled in a divorce to the increase the other spouse received by the inheritance.
Each spouse shall remain the manager of his or her personal property during marriage in Thailand.
Certain marital property must be jointly managed and other property can be managed by each spouse. A prenuptial agreement as a pre-marriage contract may grant management of certain Sin Somros (jointly owned marital property) to one of the spouses. Without a prenuptial or marriage contract certain legal acts with regards to certain jointly owned properties must be managed jointly by the husband and wife.
As a foreigner is not allowed to have joint ownership in land together with the Thai spouse land cannot be a Sim Somros and will be managed by the Thai spouse solely. An important aspect for the foreign spouse is of course the fact that the Thai spouse has full management and control over the property and in case of a divorce the Thai spouse would be able to sell the property without the consent of the other spouse.
Also if the Thai spouse dies the foreigner has to deal with other heirs of the Thai spouse unless a last will has been made.
If protection is required the first protection for the foreign spouse lies in registering joint or sole ownership over the building separate from the land. It's only the land aspect of the property that is restricted for foreign ownership, not the structures upon on the land or immovable property as a whole. It most cases land and house will be registered together in the Thai spouse's name. The structures on the land can be a jointly owned property or even owned as a personal property of the foreign husband.
By registering ownership or co-ownership over the house in a separate procedure at the Land Department the foreign spouse prevents a situation where the Thai spouse is able to sell the whole property without the consent of the other spouse (see section 1476 'management of Sin Somros' above). The house will be a Sin Somros therefore must be jointly managed by both spouses and selling would need both spouses consent (unless a valid prenuptial agreement has been made).
The second option for protection lies in registering a right of usufruct, or in case of undeveloped land a right of superficies over the property in the foreign spouse's name at the Land Department. A rights of usufruct or superficies registered on the title deed is an acceptable protection for a foreign spouse, especially if the money expended on the property comes from personal property of the foreign spouse.

Samuiforsale provides general Thai legal information and law resources in English over the Internet. The information in Samuiforsale should be used as general Thai legal information in English but should not be treated as a substitute for specific legal advice concerning individual situations.