Reviewed by ThaiLawOnline, a licensed Thai law firm practising in Thailand since 2006. Thai lawyer of record: Wichuda Atthamethakon, LL.M., Thai Bar Licence 3149/2556.
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Legitimation (การรับรองบุตร, rap rong but, also called legitimization or acknowledgement of paternity) is the act by which a child born to unmarried parents becomes the legitimate child of the father. Under Section 1546 of the Civil and Commercial Code a child born out of wedlock is the legitimate child of the mother alone, whatever the birth certificate says. Section 1547 gives the father three ways to change that: marrying the mother, registering at the district office, or obtaining a court judgment. Until then he has no parental power.
Table of Contents
The three routes under Section 1547
Subsequent marriage. If the parents register their marriage after the birth, the child becomes legitimate automatically.
Registration at the amphur. The father applies at the district office, and under Section 1548 both the mother and the child must consent. If either does not answer, the registrar notifies them, and silence for 60 days (180 days if they are outside Thailand) counts as refusal. Registration makes the man the legal father and, with the mother, a holder of parental power (Section 1566). The exception is Section 1549: within 90 days of being notified, the mother or child may have the registrar record that he is unfit to exercise parental power in whole or in part, and he then cannot exercise that part until a court rules in his favour or 90 days pass without them asking the court to confirm it.
Court judgment. Where the mother or child objects, does not consent or cannot consent, Section 1548 requires a court judgment: the father petitions the Juvenile and Family Court, and if the court rules that he may register the child, the registrar registers it on production of the judgment. Separately, a child can sue a man to be declared his legitimate child, and Section 1555 then presumes paternity on listed facts, including a written acknowledgement by the father, his name on the birth register with his knowledge or consent, open cohabitation with the mother when she could have conceived, or the child being generally known as his.
Practical points for a foreign father
The common misunderstanding is that a Thai birth certificate naming the father makes him the legal father. It does not; it is evidence of a fact, and under Section 1546 the mother remains the sole holder of parental power. A foreign father who has lived with the mother for years still cannot object if she takes the child abroad or blocks contact.
At the amphur the father brings his passport, the child’s birth certificate, the mother’s identity card and house registration, and certified Thai translations of foreign documents; the mother and child attend to consent. The court route commonly takes six months to a year. Under Section 1557 the effect is retroactive to birth, which cuts both ways: the father gains inheritance rights and standing, and takes on the duty of maintenance under Section 1564 from the birth: in Supreme Court Decision 7345/2560 the child recovered support from birth to the filing date in the same action that established paternity. The retroactive effect cannot be used against a third party who acted in good faith before the legitimation (Section 1557).
What legitimation does and does not give
Legitimation creates the legal relationship of father and child: mutual inheritance rights, the maintenance duty, the child’s right to the father’s surname, and standing to ask the court for custody or contact. It also makes the father a joint holder of parental power with the mother, subject to a Section 1549 objection. It does not give him sole parental power, which needs an agreement the law recognises or a court order, and it does not by itself entitle him to take the child abroad without her consent.
Time limits matter. Under Section 1556 a child under 15 sues through a legal representative, a child of 15 or more must sue in person without needing that consent, and a child who has come of age must sue within one year of coming of age. A registration can be revoked under Section 1554 on the ground that the man who registered is not the father, in an action by an interested person brought within three months of learning of the registration and at most ten years after it.
Last reviewed: 27 September 2026. Civil and Commercial Code sections 1546 to 1549, 1552, 1554 to 1557, 1564 and 1566, and sections 30 and 31 of the Conflict of Laws Act B.E. 2481, were read in Thai, with Supreme Court Decision 7345/2560 read to its disposition. The document list for the district office and the time the court route takes are practice points, not checked against a statute in this review.
Frequently asked questions
Can a foreign father legitimate a child in Thailand?
Yes. Section 1547 applies to any father, but under Section 31 of the Conflict of Laws Act B.E. 2481 legitimation is governed by the national law of the father at the time, so the law of his own country matters too. A foreigner registers at the amphur with the mother’s and child’s consent, bringing a passport and certified Thai translations, or petitions the Juvenile and Family Court where consent is refused.
Does legitimation give the father custody in Thailand?
Not sole custody. Legitimation makes him the legal father and a joint holder of parental power with the mother under Section 1566, unless within 90 days of notice the mother or child has the registrar record that he is unfit, in which case he cannot exercise it until a court rules for him or 90 days pass without them going to court (Section 1549). Sole parental power needs a court order or an agreement the law recognises.
What if the mother refuses to consent to legitimation?
Under Section 1548 the registration then needs a court judgment. The father petitions the Juvenile and Family Court, and if it rules that he may register, the registrar registers the child on production of the judgment, with legitimacy running from birth under Section 1557. A child can also sue a man to be declared his child under Section 1555, which lists facts from which paternity is presumed.
See also: parental rights, child custody, full (sole) custody, travel consent letter, and the full guides to legitimation of a father’s rights in Thailand and child custody in Thailand.
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