Is there some math formula how to calculate common marital assets between husband and wife in Thailand when the marriage ends by divorce or death, or is just everything you buy during the course of the marriage under Thai matrimonial laws considered jointly owned?
Marital or jointly owned property between husband and wife in Thailand is governed by the civil and commercial code Book 5, part 4 'property of husband and wife'. When the marriage ends jointly owned 'matrimonial' property must be divided between husband and wife. Only jointly owned property is divided equally between husband and wife and personal property is not divided. The first question when the marriage ends is if an asset is regarded as personal or jointly owned property between husband and wife.
Marital property (jointly owned property between husband and wife (section 1474)) consists of:
property acquired during marriage, (eg. money earned during the marriage and property bought from it)
property acquired by either spouse during marriage through a will of gift made in writing if it is declared by such will or document of gift to be jointly owned between husband and wife
fruits of personal property (eg. income in the form of rent from a personal asset)
Two more principles must be taken in to account;
Section 1472: if a personal asset has been exchanged to other property, other property has been bought or money has been acquired from selling it, such other property or money acquired shall be a personal asset. For example, if you buy a car during your marriage and you pay for the car with personal money (not marital) the car is a personal asset of the spouse who paid for it (if paid with personal property), even though acquired during the marriage
Section 1474: in case of doubt as to whether a property is jointly owned or not it shall be presumed to be jointly owned between husband and wife (for example, you bought a car but can't proof it is paid for with personal assets/ money it will be considered a marital property and must be divided in equal shares when the marriage ends/ in a divorcee.
Division of jointly owned assets;
Upon termination of the marriage, the marital assets shall be divided equally between man and woman. In a divorce in Thailand the division of assets is based on:
what is marital jointly owned assets (this must be divided), and
what is personal assets (this remains with each spouse).
If you can agree with your spouse on how assets are to be divided (mutual consent divorce) it is a private financial settlement between the spouses. If it has to go to court because you cannot agree with your spouse on the terms of the divorce the above generally comes down to what you can prove in front of a judge. If you bought a car and paid for it with money that is considered part of your personal assets, can you prove it in court? To prevent that a divorce in Thailand is dragging on for one party's financial gain it is recommended to make a prenuptial agreement (among others to have a clear understanding of what are personal assets at the time of marriage) and keep a form of (yearly) marital accounting during the marriage (to prevent creating a mix of personal and marital assets because in case of doubt (section 1474) property acquired during marriage will be regarded as jointly owned marital property).
In general the courts in Thailand must divide marital assets in equal shares according to section 1533 of the civil code stating 'upon divorce the sin somros (marital assets) shall be divided equally between man and woman'. A provision in a prenuptial agreement prescribing a different division of assets between husband and wife shall generally be considered void in a court pursuant section 1465 civil code.
A special situation exists for the purchase of real estate in Thailand, as this is often paid for by the foreigner, but signed away as personal assets of the Thai spouse and therefore not automatically divided as a marital home.