ZURICH, SWITZERLAND – A Swiss man faces a forced surname change after his father’s Thai naturalization 46 years ago created a bureaucratic legacy that no one expected.
The Zurich Case: 46 Years and a Wrong Name
A man from the canton of Zurich received a letter from the cantonal municipal office after his father’s death. It stated that his surname did not match what was recorded in the Thai register. His father had naturalized in Thailand in 1979 and adopted a Thai name as required by authorities. The son, born shortly after in Switzerland, received the Swiss surname. No one informed the Swiss authorities about the new Thai name at the time.
After Thailand transmitted the death documents, the discrepancy became apparent. The Zurich municipal office considered itself legally obliged to correct the register. The ombudsman’s office called the outcome “extremely unsatisfactory” but saw no room for maneuver. Two options remain: the affected person voluntarily agrees to the name change and later changes it back, or a court decides.
Why Thailand Requires a Thai Name
There is no explicit law stating that foreigners must give up their names. The practice is based on the Nationality Act B.E. 2508 of 1965 and the Person’s Name Act B.E. 2505 of 1962. The latter requires that every surname in Thailand be unique and no longer than ten Thai letters. Anyone naturalizing must register in the household register and needs a Thai name that complies with the rules.
The historical root lies in the Nationality Act of 1939, which forced applicants—especially Chinese immigrants—to abandon their foreign names and adopt a Thai name. This requirement has softened legally but remains in administrative practice. Today, the Special Branch Police and the Interior Ministry simply do not approve citizenship applications without a Thai name.
What Thai Naturalization Specifically Requires
The path to Thai citizenship begins with Permanent Residence status, which must be held for at least five years. Those without a close relationship to Thailand need a monthly income of at least 80,000 Baht taxed for three years. For marriage to a Thai citizen, the threshold is 40,000 Baht per month. A criminal record check, language skills, and singing the national and royal anthems are also required.
Since a cabinet decision in January 2022, a Thai language test is formally mandatory; a subcommittee examines candidates, or a certificate of completion of Thai primary school suffices. The final decision lies with the Interior Minister, who submits the application to the King for royal approval. The new name then appears in the Royal Gazette. The process takes five to ten years in practice, often longer. There is never a legal entitlement to naturalization.
Dual Citizenship: What Really Applies
Thailand formally requires a renunciation of previous nationality but rarely enforces this for Western Europeans. Since 1992, it has not been illegal to hold multiple citizenships in Thailand. Thai citizens who acquire another nationality do not automatically lose their Thai citizenship unless they actively renounce it. For naturalized Westerners, this usually results in a silent dual citizenship.
The other side of the equation is the home country. Germany has allowed dual citizenship for all applicants since June 2024. Switzerland also recognizes dual citizenship. A Swiss person who becomes a Thai citizen does not risk losing their Swiss passport—but they do change their name, at least in Thai registers.
The Problem with the New Name and Children
Here lies the trap revealed by the Zurich case. Anyone who adopts a Thai name in Thailand carries two different names in two registers. In Thailand, the Thai name appears; in Swiss, German, or Austrian civil status registers, the original surname remains. As long as everyone involved is alive and nothing happens, the problem stays invisible. When the naturalized person dies, Thai authorities transmit death documents with the Thai name, and the discrepancy surfaces.
Children born after the father’s naturalization in Thailand would theoretically have inherited the Thai name. Those who did not actively coordinate the matter—and hardly anyone did in 1979—face a name register that no longer matches decades later. The affected person in Zurich was advised by the ombudsman’s office to agree to the change and then change his name back through the courts. He bears the costs and effort himself.
What to Do Now
Anyone seriously considering Thai citizenship should treat the name change as an international legal problem from the start—not as a mere Thai formality. Inform the consulate or embassy of the home country, actively notify Swiss, German, or Austrian civil status authorities of the naturalization and new name, and clarify the impact on children and inheritance law. Those who fail to do so push the problem into the next generation.
For expats planning their retirement in Thailand without seeking citizenship, the problem does not arise in this form. But those who want to take the final step after decades in the country need legal guidance—in Thailand and at home. A legal adviser specializing in expats can clarify the consequences for the home country in advance, before the Thai name appears in the Royal Gazette.
Editorial Notes
This article provides general information on the legal situation in Thailand and Switzerland. It does not replace individual legal or tax advice. For personal cases, contact a licensed attorney in Thailand and in the respective home country.