Thai citizenship by descent: through your mother or father

Maybe your mum is Thai and you grew up somewhere else. Maybe your dad is Thai and your parents never married. Either way, the question is the same: does Thai nationality pass to you? This page covers only that: how Thai nationality passes from a parent. It does not cover naturalisation.

What does Thai law say about citizenship by descent?

The rule is in section 7(1) of the Nationality Act B.E. 2508 (1965), as rewritten in 1992. In the unofficial English translation made for the Office of the Council of State, the following persons acquire Thai nationality by birth:

“(1) a person born of a father or a mother of Thai nationality, whether inside or outside the Kingdom of Thailand”

Thailand’s Ministry of Foreign Affairs says the same in plain words: “A child who was born to either or both Thai parents is qualified for Thai citizenship.”

Two things to keep in mind. The translation itself says it “contains no legal authority”, that it is an initial version pending review by the Office of the Council of State, and that the original Thai text is the only one with legal force. And a rule in an Act is not a ruling on your family. How it applies to you is for Thai officials to decide, from your family’s papers.

Am I a Thai citizen if my mother is Thai?

The Act names a Thai mother and a Thai father side by side, and it doesn’t matter whether you were born in Thailand or abroad. The London embassy puts it simply: “Under Thai law, a child gets his/her Thai citizenship after the Thai mother.”

For a child born abroad to a Thai mother, the Ministry of Foreign Affairs says the mother “will have to notify the Thai embassy and/or consulate-general so that a Birth Certificate can be issued to prove that the child holds a Thai nationality.” That is the step that puts you on paper. How to do it is in our guide to getting a Thai birth certificate for a child born abroad.

Can you get Thai citizenship through your father?

The Act names a Thai father in the same words as a Thai mother. The extra questions come up when your parents were not married to each other.

What the Ministry of Foreign Affairs says. A child born to a Thai father who did not register a marriage with a foreign mother “will be qualified for Thai citizenship by”:

1. the subsequent marriage of the parents,
2. a Legitimate Child Registration made on application by the Thai father, or
3. a court order on the legitimate child of the father.

What the London embassy says. If the parents are not married and the mother is not Thai, “the child will get Thai citizenship only after the father has registered the child as his.”

What the Act says since 2008. The Nationality Act (No. 4) B.E. 2551 added a second paragraph to section 7. In the unofficial translation: the word “father” in (1) “shall include a person having been proved, in conformity with procedures prescribed in Ministerial Regulation, that he is a father of the newborn, even if he does not register marriage with the mother of the newborn, nor register the newborn as a legitimated child.” Section 21 of the 2008 Act says this also applies to people born before it came into force. The Act was published in the Royal Gazette on 27 February 2008 and took effect the next day. Its published reason mentions the many people born in Thailand to Thai fathers who did not get Thai nationality by birth because the father had not married the mother or legitimated the child.

Where that leaves you. The Act and the embassy pages describe different paths. We don’t know how a given embassy applies the 2008 rule, or which proof the ministerial regulation asks for. Canberra says any case with a Thai father and a non-Thai mother needs “a process concerning scientific proof of biological parenthood” and asks you to contact them first. Ask your embassy which route fits your family, before you send anything.

What if you were born before 1992?

Section 7(1) in its current form came from the Nationality Act (No. 2) B.E. 2535, published in the Royal Gazette on 25 February 1992 and in force from 26 February 1992. Its section 10 says the new section 7(1) “shall also apply to people born before the date this Act came into force” (our translation of the Thai text).

Embassies treat these older births as a separate process:

• London has a separate section for a child “born before 1st March, 1992 (B.E. 2535)”: the usual forms, a full UK birth certificate certified first by the FCO Legalisation Office, a £10 cash fee, and both father and mother attending in person.
• Chicago links an interview form to “request a retroactive birth certificate for a child born before 1992 to acquire Thai nationality (under Section 10 of the Nationality Act, Amendment No. 2).”

We couldn’t find an official English page that explains what the rule was before 1992, so we don’t describe it here. If you were born before 1992, write to your embassy first.

Does registering a birth make you Thai, or just prove it?

The Act says nationality through a Thai parent is acquired by birth, and the Ministry of Foreign Affairs says the embassy birth certificate is issued “to prove” Thai nationality. Those two sources describe the certificate as proof of something that comes with birth.

Some embassy wording reads differently, though. Chicago speaks of a retroactive certificate “to acquire Thai nationality”, and London says a child of an unmarried Thai father gets citizenship “only after” he registers the child. We can’t settle that from a web page, and it may matter for your family, so ask your embassy how it reads your case. Our Thai passport guide covers what embassies ask for after the birth certificate.

How do the scenarios compare?

This table only repeats what the sources say. It can’t tell you whether you are Thai.

Can an adult who was never registered still apply?

Some embassies describe how. Canberra says “In case that the children are above 15 years old, they can apply for their birth certificates themselves.” Washington DC says that if the applicant is over 20, the applicant and the person reporting the birth both come in person, and anyone over 15 shows an original photo ID. None of the pages we read gives an age limit or a deadline. If you’re an adult and were never registered, a short email to your embassy explaining your situation is a good first step. Asking is always fine.

Can you lose or give up Thai nationality?

Giving it up is done by a declaration or an application to Thai officials under sections 14 and 15 of the Act, and whether you can hold two nationalities depends on both countries. Our Thai dual citizenship guide covers what official pages say. Thai nationality also comes with duties; for sons, see what Thai embassies say about military service.

What we couldn’t confirm

We only publish what an official source says. These had no official answer we could find:

• The rule before 1992. We found no official English page on how nationality passed from a Thai parent before the 1992 amendment.
• How embassies apply the 2008 “proven father” rule, and which proof the ministerial regulation asks for.
• Two dates. The 1992 Act took effect on 26 February 1992, but London’s page uses 1 March 1992 for its older-births process. We don’t know why.
• Whether registration grants or records nationality. The Act and the Ministry point one way, some embassy wording the other.
• Grandparents. Section 7(1) speaks of a father or mother. We found no official page on descent through a grandparent alone.

We re-check this guide at least every 90 days. Before you act on any of it, confirm with your embassy.