Does Thailand allow dual citizenship? Sweden, UK, US

Can you hold Thai and another citizenship at the same time?

Often, yes, but two countries get a say, and each one decides only about its own nationality.

• Your other country decides whether you can keep its citizenship while you are also Thai. Sweden, the UK and the US all allow dual citizenship.
• Thailand decides whether you are Thai. We found no official Thai page that states a general rule on dual nationality. The clearest official wording is a diplomatic note from the Royal Thai Embassy in Bern, dated 28 August 2019, which says that the Nationality Act of Thailand “does not stituplate specifically in forbiding any Thai national to hold dual citizenship” (spelling as in the original).

That note is an embassy letter to the Swiss authorities, not the Act itself. Nobody can promise you an outcome from a web page, including us.

Are you already Thai?

You may be Thai on paper already. Thailand’s Ministry of Foreign Affairs says “A child who was born to either or both Thai parents is qualified for Thai citizenship”. For a child born abroad to a Thai mother, it says the mother should notify the nearest Thai embassy or consulate so a birth certificate can be issued. If your Thai parent is your father and your parents were not married, the Ministry describes extra steps, such as legitimation by the father. In practice it usually starts with a Thai birth certificate from the Thai embassy. Our Thai passport guide walks through the paper trail from there. For how Thai nationality passes from a mother or a father, and where the law and embassy pages differ, see Thai citizenship by descent.

Can you be Swedish and Thai?

Sweden allows it. Migrationsverket says: “Sverige tillåter dubbelt och flerfaldigt medborgarskap” (Sweden allows dual and multiple citizenship). Sweden Abroad confirms the rule has applied since 1 July 2001.

Migrationsverket also notes the main risk: your other country may not recognise your Swedish citizenship.

One rule to know if you were born outside Sweden. Migrationsverket says you lose Swedish citizenship at 22 if you were born outside Sweden, have never lived there, and have not spent time in Sweden in a way that shows ties to the country. You can apply to keep it after turning 18 and before turning 22, at a Swedish embassy or consulate, and there is no fee. You don’t need to apply if you have lived in Sweden or visited regularly. This matters most for luk khrueng who grew up in Thailand with a Swedish parent.

Can you be British and Thai?

The UK allows it. GOV.UK says: “Dual citizenship (also known as dual nationality) is allowed in the UK.”

GOV.UK also says that as a dual national you can’t get diplomatic help from the British government while you are in your other country of nationality. For a British and Thai citizen, that would mean in Thailand. For travel, the UK advises that “it is best to leave Thailand on the same passport you used to enter”, and British citizens returning to the UK must carry a valid British passport or certificate of entitlement. Thai embassy pages say the same about leaving on the passport you entered on; see our guide to which passport to use when entering Thailand.

Can you be American and Thai?

US law allows it. The US Department of State says “U.S. law does not require a U.S. citizen to choose between U.S. citizenship and another (foreign) nationality.”

It also says three things worth knowing:

1. “U.S. dual nationals owe allegiance to both the United States and the foreign country”, and each country can apply its own laws to you.
2. US citizens, including dual nationals, “must use a U.S. passport to enter and leave the United States.”
3. US consular help may be limited in the country of your other nationality.

How do the three countries compare?

What does Thailand’s side say?

Here is everything we found on official Thai pages, and nothing more.

• Descent: a child of a Thai mother or father qualifies for Thai citizenship (Ministry of Foreign Affairs).
• No specific ban: the 2019 Bern note says the Nationality Act does not specifically forbid dual citizenship.
• One Thai passport: “Thai nationals can only hold one Passport” (Ministry of Foreign Affairs). That means one Thai passport. It says nothing about your other one.
• Giving up Thai nationality is an application. The Brussels embassy describes it under Sections 14 and 15 of the Nationality Act B.E. 2508 (1965): applicants must be at least 20, and the process “takes approximately 3 years or longer”.

“You have to choose at 20.” You’ll read this on forums. We found no official Thai page that says a dual national loses Thai nationality automatically at 20, so we can’t confirm it. If it worries you, ask your embassy in writing.

The other parent’s country can change the picture. The Thai embassy in Singapore writes that a child whose father has Singapore citizenship, once the child reaches legal age, “will not able to hold dual citizenship” (spelling as in the original), and must give up Singapore citizenship first to apply for Thai citizenship. That comes from Singapore’s side of the rules. It shows why you need to check both countries, not only Thailand.

What duties come with Thai nationality?

Being Thai on paper comes with Thai rights and Thai duties. The one families ask about most is for boys and men. Embassy pages say the duty to register for military selection covers Thai men abroad too. The Oslo embassy writes: “Any Thai male with several citizenships, holding Thai birth certificate is obliged by law to undergo conscription.” The 2019 Bern note says the same for adopted Thai boys who keep Thai nationality. Our guide to what Thai embassies say about military service covers registration and deferment.

Who should you ask?

1. The Thai side: the Royal Thai Embassy or consulate for where you live. Our Thai passport guide lists their websites.
2. The Swedish side: Migrationsverket, or a Swedish embassy if you live abroad.
3. The British side: GOV.UK and the Home Office.
4. The US side: the U.S. Department of State, or a US embassy or consulate.

A short email that gives your birth country, your parents’ nationalities and the documents you already hold usually gets the most useful answer. Asking is always fine.

If someone at a Thai bank or office asks about your nationality, this is how to say it. The phrase comes from the “Living in Thailand” lessons in Reply Thai.

ถือสองสัญชาติ

thue sorng san-chaat

ถือสองสัญชาติครับ

thue sorng san-chaat khrap

ถือสองสัญชาติค่ะ

thue sorng san-chaat kha

Who is speaking?

ครับ said by a manค่ะ said by a woman

Draft: waiting for a native speaker’s review.

What couldn’t we confirm?

We only publish what an official page says. These have no official answer we could find:

• a general statement from the Thai government on dual nationality (beyond the 2019 embassy note)
• whether anyone loses Thai nationality automatically at a certain age
• which passport a dual national must use to enter Thailand

We re-check this guide at least every 90 days.

Thai words on this page are a draft until a native speaker has reviewed them.