Becoming a Thai Citizen: Naturalization, Marriage to a Thai and What the Nationality Act Requires

Published 9 November 2026 · By the Visit-Thailand editorial team · Editor: Terje Moy

A foreigner can become a Thai citizen in two ways: by naturalization under section 10 of the Nationality Act, which in practice requires at least five years of permanent residence, income, Thai language and good conduct, or, for the foreign wife of a Thai, by a simpler application under section 9. Both routes end with a decision at the Minister of Interior's discretion, and the applications are handled by the Special Branch Bureau of the Royal Thai Police.

Citizenship is the last step in a long residence, not a visa option, and the requirements are strict: the Special Branch criteria include a minimum monthly income, three years of Thai tax returns, an interview in Thai and the ability to sing the national and royal anthems. This page explains the law and the official checklists as published in November 2026. It is not legal advice; for your own case, talk to Special Branch and a licensed Thai lawyer.

What the Nationality Act says

The Nationality Act was given on 21 July 1965 and has been amended several times, most importantly in 1992, 2008 and 2012. Four sections matter to a foreign applicant:

• Section 9 lets "an alien woman who marries a person of Thai nationality" apply for Thai nationality. The decision lies with the Minister.
• Section 10 sets the naturalization conditions: the applicant must be of age under Thai law and their own country's law, of good behavior, with a regular occupation, domiciled in Thailand for at least five consecutive years before applying, and with knowledge of Thai as set by regulation.
• Section 11 waives the five-year domicile and the language condition for some applicants, including people who have rendered distinguished service to Thailand, former Thai nationals, the spouse or child of a naturalized Thai, and, since the 2008 amendment, the husband of a Thai national.
• Section 12 covers the application itself. Minor children living in Thailand can be included. If the Minister approves, the application goes for Royal Sanction, the applicant makes an affirmation of loyalty, and a certificate of naturalization is issued after publication in the Government Gazette.

Thai nationality by birth is a different subject, under section 7. A child with a Thai father or mother is Thai from birth; our guide to having a baby in Thailand explains how that works and what applies when both parents are foreign.

Naturalization: the Special Branch criteria

The Act is short, so the detail comes from the criteria Special Branch applies, approved by the Deputy Minister of Interior on 14 October 2009 and still published on its Nationality Service Center page in 2026. An applicant under section 10 must meet all of these:

1. Legal age under Thai law and the law of their own nationality.
2. Good behavior, checked by fingerprints and a criminal-record search, including drugs, national-security matters and foreign arrest warrants.
3. A regular occupation, with a certificate from the Office of Foreign Workers Administration or the provincial employment office; for most applicants that means a job held on a work permit and Non-B visa.
4. Minimum income: at least 80,000 baht a month with three years of income tax paid, for an applicant with no family tie to Thailand. The figure drops to 40,000 baht a month for someone married to a Thai, with a Thai child, or holding a Thai university degree. As an alternative, Special Branch accepts personal income tax of at least 100,000 baht a year for three years (50,000 baht in the lower tier).
5. Lawful residence shown by a residence certificate (permanent residence), an alien identity book or a Tor Ror 14 house registration.
6. Five years of domicile, counted from the date that residence document was obtained.
7. Thai language: the ability to speak and understand Thai and to sing the Thai National Anthem and the Royal Anthem, tested in an interview.
8. A letter from your embassy stating that you intend to renounce your original nationality once naturalization is granted.
9. At least 50 points on Special Branch's scoring sheet.

Two of these decide most cases. The first is permanent residence: because the five years run from the residence certificate, a long stay on yearly extensions, such as the retirement visa, does not count on its own. Our page on permanent residency in Thailand covers the quota and the application rounds. The second is Thai. The interview is held in Thai, so the language is not something to leave to the final year; an education visa for learning Thai is one way to study it full-time. The scoring sheet itself is not attached to the published guidance, so we could not confirm how the points are given.

The documents and the fee

Special Branch's own English checklist for naturalization includes copies of your alien identity book and residence certificate, your work permit, passports and house registrations, a translated marriage certificate if you are married, personal income tax returns for the past three years certified by the Revenue Department (our guide to filing a Thai tax return explains the forms), an employer's salary certificate, education certificates, two Thai witnesses, a bank deposit of at least 80,000 baht, and proof of charitable donations of at least 5,000 baht made over time, not just before applying. Shareholders also bring company documents.

You apply in person. The fee is 5,000 baht with the application, plus 100 baht for the fingerprint and criminal-record check. Bangkok applicants are interviewed by a screening sub-committee; in the provinces a provincial working group does it. No official processing time is published, so treat any figure you see online with caution.

The foreign wife of a Thai: section 9

The section 9 route is separate from naturalization and much lighter. Special Branch's form for it, called Kor Chor 1, sets these conditions:

• The marriage must have been registered for at least three years, or at least one year if the couple have children, counted up to the date of application.
• The Thai husband must show an income of at least 20,000 baht a month, with his latest personal income-tax return; if the wife works, her income can be added to reach that amount.
• Four personal witnesses with Thai ID cards confirm that the marriage is genuine.
• The fee is 5 baht for the application plus 100 baht for the fingerprint check.

Where you apply depends on where you live: in Bangkok, to the Commissioner of the Special Branch Bureau; in another province, to the provincial police commander; abroad, through the Thai embassy or consulate. The section 9 checklist does not list permanent residence, a Thai-language test or an embassy renunciation letter. The registered marriage is the foundation, so our guide to marrying a Thai citizen is the place to start if that step is still ahead.

The foreign husband of a Thai

Section 9 speaks only of a foreign woman, so a foreign husband has no section 9 route. That does not mean he has no route. Since the 2008 amendment, section 11 (4) waives the five-year domicile and the Thai-language conditions of section 10 for "a husband of a person with Thai nationality", and he applies by naturalization.

In practice the Special Branch criteria still ask naturalization applicants for permanent residence, an interview in Thai and the two anthems, and they do not set out a separate list for husbands. The lower income threshold of 40,000 baht a month applies to applicants married to a Thai. Ask Special Branch how the waiver is applied in your case before you prepare the file.

Dual nationality in practice

We found no single official sentence saying that Thailand allows or forbids dual nationality. What the official texts show is this. Thais who are dual nationals from birth can usually keep both, because the Act gives them renunciation as an option rather than a requirement. Foreigners who naturalize are expected to give up their original nationality, as the embassy letter shows. Section 19 also lets the Minister revoke a naturalized person's Thai nationality if there is evidence that "he still makes use of his former nationality", or if he lives abroad for more than five years without a domicile in Thailand.

Whether the section 9 route for wives involves renunciation is not stated in the published checklist, so we make no claim either way. Your own country's rules matter just as much, so ask your embassy what taking Thai nationality would mean for your current citizenship.

After approval: registration, ID and names

Once the certificate of naturalization is issued, your civil registration changes too. Long-term residents who are not Thai use the yellow Tor Ror 13 house book and, if they wish, a pink ID card; our page on the yellow house book and pink ID card explains those documents and the registration office. Ask the district office what you need to transfer to a Thai house registration and a Thai ID card.

Your name will be written in Thai script on every document from then on. How Thai first names, surnames and titles work is explained in our guide to Thai names and nicknames.

Getting help with an application

The Special Branch Bureau's Nationality Service Center is at the Public Service Centre building, 27/40 Soi Vibhavadi Rangsit 27, Lak Si, Bangkok, telephone 02-551-1999 extension 3 in office hours. Its page carries the current checklists as scanned files, mostly in Thai. A Thai lawyer can help with translations, the witnesses and the tax records; our page on hiring a lawyer in Thailand explains how to find a licensed one. Only the Minister can grant nationality, so be wary of anyone who promises a result.

Frequently asked questions

Can a foreigner become a Thai citizen?

Yes. Under section 10 of the Nationality Act a foreigner can apply for naturalization, and Special Branch practice requires at least five years of permanent residence, a minimum income, three years of Thai tax returns, spoken Thai and an embassy letter on renouncing the original nationality. The Minister of Interior decides each case.

Can I get Thai citizenship by marrying a Thai?

A foreign wife can apply under section 9 after three years of registered marriage, or one year if the couple have children, with the husband earning at least 20,000 baht a month. A foreign husband has no section 9 route but applies by naturalization, with some conditions waived by law since 2008.

Does Thailand allow dual citizenship?

Thais who hold two nationalities from birth can usually keep both. Foreigners who naturalize are expected to renounce their original nationality, and Special Branch asks for an embassy letter stating that intention. The Minister can also revoke a naturalized Thai's nationality for using the former one.

How long does Thai naturalization take?

No official processing time is published. After Special Branch's checks and interview, an approved application goes to the Minister of Interior, then for Royal Sanction and publication in the Government Gazette, so expect a long process and ask Special Branch about current timing.

Do I need permanent residence to become Thai?

For naturalization under section 10, yes in practice: the Special Branch criteria count the five years from the date you obtained the residence certificate or an equivalent document. The section 9 route for foreign wives of Thai men does not list permanent residence among its requirements.

Sources

• Special Branch Bureau, Royal Thai Police – Nationality Service Center (Thai) (checked November 2026)
• Special Branch Bureau – Evidence required to apply for naturalization as a Thai (checked November 2026)
• Special Branch Bureau – Guidance on applying for naturalization as a Thai (Thai) (checked November 2026)
• Special Branch Bureau – Thai nationality for the foreign wife of a Thai, section 9 (Thai) (checked November 2026)
• Nationality Act B.E. 2508 as amended to No. 5 B.E. 2555, unofficial English translation (ecoi.net) (checked November 2026)