You have remarried, your spouse's child lives in your home, you have raised the child like your own, and you want the law to recognise that. Adoption is possible, but it starts with the child's and the birth parents' documents, not with filing an application. If your worry is that the other birth parent is not paying support, see child support and parental power. If you are planning to move the child abroad, see taking a child abroad and consent.
The core answer
This guide covers only the case where a new spouse wants to adopt the other spouse's child: what to check first, who must consent, what the steps are, and how the effects on family rights and inheritance differ. The main rules on parental power after divorce are in the divorce, custody and property guide.
The legal rule (Civil and Commercial Code). Section 1598/19: the adopter must be at least 25 and at least 15 years older than the child. Section 1598/20: a child of 15 or older must also consent. Section 1598/21: adopting a minor needs the consent of both parents, with a way forward if one has died, lost parental power, cannot be found, or refuses without reasonable cause. Section 1598/25: the spouse of the adopter or of the child must consent. Section 1598/27: adoption is complete on registration, and for a minor the law on child adoption must be followed first. Section 1598/28: the adopted child has the status of the adopter's legitimate child but does not lose rights and duties in the birth family.
Our practical view. Matters usually stall on two points: not knowing who holds parental power according to the actual documents, and the other birth parent being unreachable or unwilling to sign. Check both before paying any fee or booking any agency appointment.
Hypothetical example. Nida lives in Khon Kaen. She married and divorced Anucha, who lives in Udon Thani, and the divorce record gave Nida sole parental power over their daughter Fah, aged 9. Nida then married Phum, aged 41, who has helped raise Fah for two years. Phum wants to adopt Fah. Anucha has not been in touch for two years and has paid no support. What needs checking is the divorce record, any court order, Anucha's latest address, and whether the agency that receives the application needs his consent. Do not conclude that he must sign or need not sign until the documents have been checked.
1. Start with the child's current status
Before thinking about adoption, answer these questions with documents, not memory.
| Question | Why it matters |
|---|---|
| Who are the parents in law? | A child born to unmarried parents is the father's legitimate child only if the parents later marry, the father registers the child, or the court adjudges the child to be his (section 1547). Without one of these, the birth father may not yet be a father in law, which affects who must consent. Check case by case. |
| Who holds parental power? | Check the divorce record, agreement or court order, because section 1598/21 ties consent to the parents and to whoever still holds parental power. |
| Is the other birth parent alive and reachable? | A death needs a death certificate. Being unreachable needs evidence of attempts to find the person. |
| Is there a court order on the child's care? | If so, it must be attached and followed. |
| How old is the child? | At 15 or older the child must consent personally (section 1598/20), and a child who has not reached majority goes through the Child Adoption Act procedure. |
| Does the child or the adopter have a spouse? | That spouse must consent (section 1598/25). |
For acknowledging a child (legitimation by the father), see the child support and parental power guide, which covers parents who never registered their marriage.
2. What must the adopter satisfy?
- At least 25 years old and at least 15 years older than the child (section 1598/19). Both must be met.
- If the adopter has a spouse, that spouse must consent. Here the spouse is already the child's parent, so consent is usually easy to give, but you still need paperwork. If the spouse cannot consent, or has been away from home and cannot be found for at least a year, a court order is needed instead (section 1598/25).
- If the child has a spouse, that spouse must also consent (section 1598/25).
- A child aged 15 or older must consent (section 1598/20). Ask the child in language the child understands, rather than having the child sign because an adult asked.
3. Who must consent, and what if a parent has died, cannot be found, or refuses
Section 1598/21 sets the framework. Adopting a minor needs the consent of both the father and the mother. If one has died or lost parental power, the consent of the other, who still holds parental power, is used.
| Situation | The route the law opens |
|---|---|
| Both parents are alive and consent | Sign written consents and register through the proper process |
| One parent has died | Use the consent of the other parent who still holds parental power; attach the death certificate |
| One parent has lost parental power | Use the consent of the other parent who still holds parental power; attach the court order |
| No one is able to consent, or one or both parents cannot express consent | An interested person asks the court for an order in place of consent |
| One parent refuses | The court can be asked where the refusal is without reasonable cause and against the child's welfare; the court looks at the facts of each case |
| Parents divorced and only one holds parental power | Check the divorce record and court order, then ask the receiving agency whom it requires consent from |
Under section 1598/21, those who may ask the court are the mother or father, the person wishing to adopt, or the public prosecutor. A parent's silence or non-payment of support does not remove the need for consent automatically; the agency or the court must be shown evidence case by case.
What not to do. Do not get a birth parent to sign by saying it is a different document. Do not forge a signature. Do not use visits or support payments as a bargaining chip for a signature. Consent obtained by deceit or pressure can be challenged and can undo the whole process.
4. The steps for a minor
Section 1598/27 says adoption is complete on registration, and for a minor the law on child adoption must be followed first. That law is the Child Adoption Act B.E. 2522.
- File the application. Under section 20, an applicant domiciled in Bangkok or abroad files with the Director-General, and one in another province files with the provincial governor. The work now sits with the Department of Children and Youth, Ministry of Social Development and Human Security, and the ministry's provincial offices. Names and filing channels can change, so telephone first.
- Check suitability and facts. Officials interview the applicant and the child, review documents, and usually visit the home (a home study). The details are agency practice.
- Trial care. Section 19 sets the rule that adoption requires trial care and approval, with exemptions for certain relatives named in the law and other persons under a ministerial regulation.
- Register the adoption. Once approved, the adoption is registered at the registration office, and it is complete only on registration.
What we could check and cannot confirm is whether adopting a spouse's child is exempt from trial care or other steps. The text of section 19 that we read does not state this case directly, and we have not found a ministerial regulation confirming it. So treat the agency as the decision-maker, and ask it directly whether trial care is required, for how long, and which documents can stand in for others. Do not start counting time or plan a registration date until you have the answer in writing.
If the birth parent's consent is the problem, speak to a lawyer about a court petition under section 1598/21 first, because the court order is a document the agency will need.
5. After adoption: what changes and what does not
| Item | After adoption |
|---|---|
| The child's status | Changes. The child has the status of the adopter's legitimate child (section 1598/28) |
| Parental power | Changes. The birth parents' parental power ends from the adoption (section 1598/28). Where the adopter is the mother's spouse, check with the agency how shared exercise of parental power with the mother is recorded |
| Surname | Check with the registration office whether it changes in the same process or needs a further step. We do not state a fixed rule |
| Inheritance from the adopter | The child is a descendant like a legitimate child (section 1627) |
| Inheritance from the birth family | Not lost. The child keeps rights and duties in the birth family (section 1598/28) |
| The adopter's rights in the child's estate | The adopter is not a statutory heir merely because of the adoption (section 1598/29) |
| The other birth parent's duty to support | The law says birth-family duties are not lost, but the practical effect, for example support arrears or agreed support, must be checked case by case and should not be assumed to disappear |
| Nationality | Do not assume adoption gives Thai nationality. Check the nationality rules separately |
6. Effect on inheritance, and alternatives to adoption
What clearly changes is that the child becomes the adopter's descendant under section 1627, and so an heir in the class of children. Rights in the birth family remain under section 1598/28, so the child may inherit from both sides.
Section 1598/29 says adoption does not give the adopter the right to inherit from the child as a statutory heir, and section 1598/30 lets the adopter reclaim property the adopter gave the child, from the child's estate, if the child dies before the adopter leaving no spouse or descendants, to the extent the property still remains after estate debts. The time limit is one year from knowing of the death, or ten years from the death.
If you do not adopt. You can make a will leaving property to a stepchild just as to anyone else. The child will not be your statutory heir and you will not gain parental power, so a will fixes inheritance but not status or parental power. For choosing an executor who will look after the child's share, see choosing an executor in a will. For the general order of heirs and how an estate is divided, see inheritance and estate administration. And if a minor inherits, how far a parent can manage the property is covered in minor heirs: a parent managing the inheritance and court permission.
Do not decide from adoption alone. Check three things separately: status and parental power, the child's inheritance rights from the adopter and from the birth family, and each side's will.
7. A foreign adopter, or a child abroad
- An applicant abroad files with the Director-General under section 20, and the Act has rules for adoption by applicants abroad. Ask the agency which documents it needs from the applicant's country.
- We do not confirm that another country will recognise an adoption registered in Thailand, or give the child residence rights or nationality there. Check that country's law and its embassy separately.
- Adoption does not automatically give the child Thai nationality, and we do not state nationality rules that we have not fully checked.
- If the child lives abroad, travel and the guardian's consent are covered in the guide on taking a child abroad.
- Families of mixed nationality should prepare paperwork for both countries together, with translations certified as the agency requires.
8. If you later want to end the adoption
We summarise only, because this needs case-by-case advice. If the adopted person has reached majority, the adoption can end by agreement (section 1598/31). If still a minor, parental consent or a court order is needed, and the termination takes effect on registration (section 1598/31). A suit to end an adoption rests on the grounds in section 1598/33 and is barred after one year from knowing the ground, or ten years (section 1598/34). When it ends, the birth parents regain parental power over a child who has not reached majority (section 1598/37).
Consent request to the birth parent (adaptable template)
Send by registered mail or another method that proves receipt, and keep a copy. Do not write anything threatening or tie it to child support.
Dear [name of birth parent]
Re: Request for consent to the adoption of [child's name] by [adopter's name]
I, [name], married to [child's other parent], write to say that I wish to
adopt [child's name], aged [..], under the Civil and Commercial Code and
the Child Adoption Act B.E. 2522.
As I understand it, the effect is that the child will have the status of my
legitimate child. The birth parents' parental power ends from the date of
registration, but the child does not lose rights and duties in the original
family, including the right to inherit from you.
Please consider giving your consent voluntarily. You may ask the agency that
receives the application, or your own lawyer, before deciding, and you have
the right to refuse.
Enclosed: the agency's consent form (if any) and copies of relevant documents.
Please reply to: [phone/address] by [date].
Yours sincerely
[name/date]
If there is no reply, do not treat silence as consent. Keep proof of sending and of your efforts to trace the person, then speak to a lawyer about a court petition under section 1598/21.
Checklist
The child's documents
- Birth certificate, house registration and ID card (if any)
- Documents showing who the parents are in law, including any registered acknowledgement of the child or court judgment (if relevant)
- Divorce record, agreement or court order on parental power
- Death certificate of the birth father or mother (if deceased)
The adopter's and spouse's documents
- ID card or passport, house registration, marriage certificate
- Proof of age and of the age gap with the child (at least 25, and at least 15 years older)
- The spouse's written consent
- Proof of income and residence as the agency requires
Consents
- Consent of the birth father and mother, or documents covering death, loss of parental power or inability to locate them
- Consent of a child aged 15 or older
- Court order in place of consent (if needed)
Steps and follow-on planning
- Ask the agency about trial care and the documents required, and get the answer in writing
- Register the adoption once approved
- Check surname, house registration and nationality separately
- Review the wills and executors of both the adopter and the birth parents
Further reading
- Child support and parental power — acknowledging a child by the father, and support issues that still need separate checking
- Divorce, custody and property — where parental power after divorce comes from
- Taking a child abroad: whose consent is needed — when the child or the family must cross borders
- Minor heirs: a parent managing the inheritance — if the child inherits while still a minor
- Choosing an executor in a will — planning for a stepchild through a will
- Inheritance and estate administration — the order of heirs and how estates are generally divided
Adoption starts with the child's documents and the birth parents' consent, and its effects on parental power and inheritance must be checked separately, not concluded from one point alone.
We help families check documents, prepare court petitions in place of consent, and plan inheritance alongside. For an initial consultation, call +66 92 254 2045 or send us the details. See also our family law practice.
This guide is published by Suwanvara Law Firm — a Khon Kaen law firm established in 1986. General information only, not legal advice on a specific matter.
