Registering legitimation of a child in Thailand: documents, how it differs from marriage registration, and why it's worth doing

Many couples live together and raise their kids together, they just never registered their marriage. Some choose that on purpose, others simply haven’t found time to go to the district office, and there’s nothing wrong with either. But there’s one thing many people only find out when the baby is born: under Thai law, a father who hasn’t registered the marriage is not yet the child’s “legal father,” even if his name is on the birth certificate.

We’re not here to judge anyone. We just want to explain clearly what legitimation registration is, how it differs from marriage registration, which documents you need, and why it’s worth doing, both for your child and for the whole family’s peace of mind.

What is legitimation registration, and why do it?

Quick Answer: It’s when the father registers the child as his legitimate child. It applies when the parents haven’t registered their marriage, because without it, the child is legally the mother’s child only.

Under the Civil and Commercial Code, a child born to a mother who isn’t legally married is the mother’s legitimate child. The father can become the legal father in 3 ways:

1. The parents register their marriage later
2. The father registers legitimation of the child at the registration office
3. A court judgment that the child is his

Until one of these is done, the father’s name on the birth certificate still doesn’t give him legal parental power over the child. The clearest example is the passport. A Ministry of Foreign Affairs document states that if the parents aren’t legally married, the mother alone can sign consent for the child’s passport, using a certificate of exercising parental power (form Por Kor 14, ป.ค.14).

How is legitimation registration different from marriage registration?

Quick Answer: Marriage registration makes the parents spouses, and the child automatically becomes the father’s legitimate child too. Legitimation registration concerns only the father and the child. The parents are not spouses.

	Marriage registration	Legitimation registration
Parents’ relationship	Legal spouses	Not spouses
Child is legally the father’s	Yes, automatically	Yes, after registration
Child’s consent needed?	No	Yes (if the child is young, it goes through the court)
Rights and duties between parents, e.g. marital property	Yes	No
Suits whom	Couples ready to be legal spouses	Couples not ready for or not wanting marriage, who want the child to have a legal father

Both routes make the child the father’s legitimate child. Neither is better or worse, it depends on what suits your family. But if you’re planning to register your marriage anyway, especially while your child is still a baby, marriage registration is honestly easier, because you don’t need the child’s consent or a court process.

What do the child and father gain?

Quick Answer: The child becomes the father’s legitimate child, back to the date of birth, with inheritance rights as a statutory heir. The father has a duty to support the child, and as a rule both parents share parental power.

• For the child: becomes the father’s legitimate child, with rights to the father’s estate and a legal right to support from the father.
• For the father: Section 1566 states that a minor child is under the parental power of the father and mother, so the father has the right to make important decisions about the child together with the mother, such as schooling, medical treatment or travel.
• For the mother: someone shares legal responsibility, and if the relationship changes one day, child support is clearer.

The other side to know: after registration, things that need a guardian’s consent, like getting a passport for your child, usually need both parents’ consent, not just the mother’s. Talk it through and agree beforehand.

What documents do I need?

Quick Answer: ID cards, house registration, the child’s birth certificate, 2 witnesses with ID cards, and a court judgment if your case has to go through the court.

According to the public guide from Khan Na Yao District Office, Bangkok:

Document	Notes
Thai ID card	The father applying, and the mother giving consent
House registration (tabien baan)	Original
Child’s birth certificate	Original and a copy
Proof of name change	If anyone has changed their name
Court judgment or order	If the child can’t consent, or there’s an objection
2 witnesses	With their ID cards

Where	Fee	Approximate time
At the registration office (any amphoe or khet district office)	No fee	About 50 minutes
Outside the registration office (asking officials to register off-site)	200 baht	About 90 minutes

Each office may ask for slightly different documents. Call the Department of Provincial Administration Call Center on 1548 before you go, so you don’t carry your baby there for nothing.

My child is still a baby. How does the child give consent?

Quick Answer: The law requires consent from both the mother and the child. If the child is too young to consent, you have to petition the court for a judgment first, then take the judgment to register.

This is the part many families don’t know, and they end up taking their documents home from the district office. Section 1548 of the Civil and Commercial Code states:

• The father can register the child as his only with the consent of the child and the child’s mother
• If the mother or child doesn’t come to give consent, the registrar notifies them. If they don’t object within 60 days (or 180 days if abroad), consent is assumed
• If the mother or child objects, doesn’t consent, or is unable to consent, registration requires a court judgment

Babies and young children can’t give consent themselves, so in practice you usually need to petition the Juvenile and Family Court first. The court process has its own details. Talk to the registration office, the court you’ll file with, or a lawyer before you start. Many courts also have a public advice desk.

For families who plan to register their marriage anyway, registering the marriage makes the child the father’s legitimate child without going through this process.

When should we do it, and what should we talk about first?

Quick Answer: You can do it at any time. There’s no deadline like there is for birth registration, but the sooner you do it, the easier your child’s future paperwork. Agree first on whether you’ll register your marriage or register legitimation.

Before you go to the district office, sit down and settle these:

• Whose surname the child will use. If you want to change the child’s surname after registration, that’s an extra process at the registration office.
• Who takes the child to do important paperwork, such as passports and health coverage
• If you separate one day, who looks after the child and how child support will be agreed
• Any money or inheritance you want to plan for your child

That said, the first piece of paperwork after the birth is still birth registration within 15 days. Get the birth registered first, then plan legitimation at your family’s own pace. For an overview of everything in the first 3 months, read Guide to your baby’s first 3 months

Families come in all shapes. Register whichever way suits you. What matters is that your child is fully protected by both father and mother, in real life and on paper.