Service guide
When Thai nationality is refused, revoked or lost: the grounds in the Nationality Act, the Review Committee, and what a lawyer can realistically do.
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Nationality disputes are rarely about whether someone would like to be Thai. They are about a decision that has already been made, or about a status someone assumed they had and turns out not to.
Three situations come up repeatedly. A naturalisation application is refused, and the Nationality Act makes permission or refusal a matter for the Minister's discretion. Nationality already held is revoked, on one of the grounds the Act sets out. Or nationality is lost by operation of the Act, which can happen without any decision being taken against the person at all.
The Act also creates a Review Committee on Nationality, chaired by the Permanent Secretary of the Ministry of Interior and drawing members from Defence, Foreign Affairs, Social Development and Human Security, Justice, Labour, the National Security Council, the Attorney General's office and the Royal Thai Police. Where nationality is contested, that is the machinery it moves through.
Revocation grounds by how nationality was acquired
Grounds set out in the Nationality Act B.E. 2508 (1965). Who orders the revocation depends on the ground.
| Acquired by naturalisation | Acquired by birth to a foreign parent | |
|---|---|---|
| Concealment or false statement | Naturalisation effected by concealment of facts or false statement of essential facts | Applies to nationality acquired by marriage where the marriage was effected by concealment or false statement |
| Continued use of another nationality | Evidence the naturalised person still uses their former nationality | Evidence of using, or inclining towards, the parent's or another nationality |
| National security or public order | Acts prejudicial to national security, conflicting with State interests, insulting the nation, or contrary to public order or good morals | The same grounds apply |
| Long residence abroad | Residing abroad without a domicile in Thailand for more than five years | Residing in the parent's country of nationality for more than five consecutive years after reaching legal adulthood |
| Who decides | The Minister | The Minister for long residence abroad or use of the other nationality; a Court, on the Public Prosecutor's request, for the national security and public order grounds |
Source: Nationality Act B.E. 2508 (1965), sections 16, 17 and 19
Checked August 2026
Note: A deadline most dual nationals never hear about
A Thai citizen born to a foreign father or mother who also acquires that parent's nationality, and who wants to keep the other nationality, is required by the Act to declare an intention to renounce Thai nationality within one year of turning twenty. It is an easy provision to be unaware of, and it is one of the reasons a person's assumed status and their recorded status can diverge.
Firms
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Browse all firmsThe first task is usually evidential rather than legal: establishing what the record actually says. Thai nationality by birth follows from a Thai father or mother, or from birth in the Kingdom subject to the Act's exceptions, and the Act expressly extends fatherhood to a man proved to be the father even where he never registered a marriage with the mother or registered the child as legitimated. Many disputes are really about proving one of those facts.
Where a decision has been made, the work is putting the case to the right body. The Act sets out the grounds and specifies who orders the revocation, so the argument is that the ground is not made out on the facts. Where nationality was lost rather than revoked, the Act provides routes for resumption in defined circumstances, including for a person who renounced on marrying a foreign national where the marriage has since ended, and for someone who lost nationality as a minor following a parent, who applies within two years of reaching legal adulthood.
Where the dispute touches a child's parentage, legitimation is often the practical step that resolves it, and documentary disputes frequently run through embassy documents and certified translation. Where the underlying question is a marriage record, marriage registration is where that evidence sits.
Establish the claimed basis
Birth to a Thai parent, birth in the Kingdom, marriage, naturalisation, or resumption. Each has a different evidential burden and a different set of grounds that can be raised against it.
Get the official record
What the registries and the Ministry of Interior actually hold, rather than what the family understands. Disputes commonly turn out to be record problems.
Identify the decision and the ground
A refusal, a revocation, or a loss by operation of the Act are three different problems. Revocation grounds are specified in the Act, so the response is aimed at the specific ground relied on.
Assemble corroboration
Parentage evidence, residence history, and documents from abroad, legalised and translated as required. This is usually the longest part.
Put the case to the right body
Nationality matters move through the Ministry of Interior and the Review Committee on Nationality, which the Act constitutes with the Permanent Secretary as chairperson and representatives of several ministries and agencies.
Naturalisation itself is not a right. The Act sets qualifications, including being sui juris (a legal adult under Thai law, not a minor and not under guardianship), good behaviour, a well-founded occupation, domicile in Thailand for not less than five consecutive years to the date of the application, and knowledge of the Thai language, with exemptions for certain applicants such as the spouse of a Thai citizen. Even where the qualifications are met, permission or refusal is the Minister's discretion.
That makes outcome promises in this area particularly unreliable. A firm can build and present a case, correct a record, and answer a stated ground. It cannot direct a discretionary decision.
On cost, firms set their own fees and the shape follows the work. Assembling evidence and preparing an application is bounded work that many firms will quote as a fixed fee. Contesting a revocation, or a matter that turns on reconstructing decades-old records, is normally hourly, because its length depends on registries and on the reviewing body rather than on the firm. No credible published source gives professional fee ranges for this work, so compare written quotes rather than any figure you find online.
These matters sit alongside the rest of the immigration lawyer in Thailand practice, since a person contesting nationality usually has an immigration position running at the same time.
This page is general information, not legal advice. Nationality turns on individual facts and records, so speak with a qualified professional about your own situation.
Common questions
Practical explainers on this topic: general information, not professional advice.
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