[日本語版]
Our firm gets many questions regarding US/Japan dual nationality. This article outlines key knowledge and considerations for individuals in a dual nationality situation.
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Basic Knowledge
The US does not generally restrict its nationals from having a foreign nationality. Japan, on the other hand, has a number of restrictions, which are explained further below.
Japanese nationality is formally recorded through the family registration (koseki) system, which is essentially a central “family tree” of all Japanese nationals maintained by local authorities in Japan. In contrast, US nationality is not centrally recorded. US nationals born in the US can prove their citizenship with a copy of their state birth certificate, while US nationals born outside the US must usually obtain a certificate from the federal government before applying for a passport or other proof of nationality.
The Japanese and US governments do not routinely share nationality records, but there are several ways for the Japanese government to become aware of a dual or multiple nationality situation. This most commonly occurs in connection with a Japanese passport application. All Japanese passport applications ask the applicant whether they have another nationality, and when and how they obtained it. Japanese embassies and consulates outside Japan also ask local passport applicants to provide proof of their legal status in the country where they are applying, such as a visa or resident card.
Even if they live outside the US, US citizens are required to file and pay US income taxes, and male US citizens between the ages of 18 and 25 are required to register with Selective Service for possible military conscription (although conscription has not actually taken place since the Vietnam War). In contrast, Japanese nationals are not subject to conscription, and their Japanese tax obligations are very limited as long as they live outside Japan.
Japan recognizes a legal concept of “nationality” (kokuseki), but does not recognize a legal concept of “citizenship” (shiminken). The US has slightly different legal concepts of “citizenship” and “nationality.” Citizenship entitles a person to vote in the US, while nationality entitles a person to live in the US. All US citizens are also US nationals, but some US nationals born in American Samoa or the Northern Mariana Islands are not US citizens.
Dual Nationality by Birth
Individuals can acquire dual US/Japan citizenship by either:
- being born in the US with at least one Japanese parent, or
- being born in another country with one Japanese parent, and one US citizen parent who was present in the US for a certain period of time before the birth.
The procedures for recording each citizenship depend upon where the person was born, as follows:
| Country of Birth: | US | Other Country | Japan |
| Procedure for US Nationality | State-issued birth certificate serves as proof of US citizenship/nationality. | Any of the following: (1) Report by parents to a US embassy or consulate in the country of birth to obtain a Certificate of Birth Abroad and US passport (2) Passport application within the United States (3) Filing of Form N-600 with USCIS to obtain a Certificate of Citizenship |
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| Procedure for Japanese Nationality | Registration by child’s parent with a Japanese embassy or consulate within three months of birth. Otherwise, the individual will need to take up residence in Japan before the age of 20 and register with the Ministry of Justice. | Japanese nationality will be recorded in the family register by notifying the relevant local authority in Japan. | |
A Japanese national who acquired another nationality by birth or as a child is generally required to make a “declaration of choice” by their 22nd birthday in order to keep their Japanese nationality. If they fail to do so, the Ministry of Justice may revoke their Japanese nationality after giving one month’s notice. However, a declaration of choice to keep Japanese nationality does not, by itself, revoke the person’s U.S. nationality. Many individuals who acquire dual nationality by birth are able to keep it indefinitely, as long as they do not tell the Japanese government that they intend to give up their Japanese nationality. Even if a person makes a declaration of choice to give up their Japanese nationality, they may re-acquire Japanese nationality by establishing a domicile in Japan and applying to the Ministry of Justice.
Dual Nationality by Choice
A Japanese national can become a US citizen by applying for naturalization in the US. This usually requires the Japanese national to obtain US permanent residency (a “green card”), and then live in the US for a certain period of time to satisfy “continuous residency” and “physical presence” requirements. Naturalization in the US will almost always result in the immediate loss of Japanese nationality. Article 11 of the Japanese Nationality Act states that “a Japanese national shall lose Japanese nationality when he or she acquires a foreign nationality by his or her own choice.” Furthermore, in the US oath of allegiance, every new US citizen is required to state that: “I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom or which I have heretofore been a subject or citizen.”
Conversely, a US national can become a Japanese national by applying for naturalization in Japan. This requires a certain period of continuous residence in Japan, followed by an application to the Japanese Ministry of Justice. Naturalization in Japan requires the applicant to renounce any other nationality they possess. Under US law, naturalizing in a foreign country after the age of 18 will result in the loss of US nationality if it was “voluntarily” and “with the intention to relinquish U.S. nationality,” but the US government takes a very strict interpretation of these qualifiers, and in any case where they are in question, will have a US consular officer question the individual as to whether they intended to relinquish their US nationality when they performed the act. As a result, a person ordinarily cannot lose US nationality unless they have submitted specific paperwork to the US government. It is therefore practically possible for a US national to naturalize in Japan, but continue to exercise their US nationality and maintain a US passport.
Automatic Acquisition of US Citizenship After Birth
A child who does not already have US citizenship “automatically” becomes a US citizen when they:
- Have at least one US citizen parent,
- Are under 18 years of age,
- Have lawful permanent resident status (a green card) in the US, and
- Reside in the United States in the legal and physical custody of the US citizen parent.
This provision may apply when a US citizen naturalizes, when they adopt a child from overseas, or if they had a child born overseas who did not qualify for US citizenship at birth. While USCIS must be notified in order to issue proof of citizenship, the US citizenship in this case is not granted by choice, and therefore a Japanese national who acquires US citizenship in this manner should not automatically lose their Japanese nationality.
Consequences Under Japanese Law
Individuals who attempt to maintain dual nationality in violation of Japanese law should be aware of the potential penalties for doing so. The Japanese government can determine that an individual lost their Japanese nationality due to choosing the nationality of another country. This means, among other things:
- Their Japanese passport will become invalid, and they will be unable to obtain a new one.
- If they are in Japan, they may be considered to be illegally present in the country.
- Their children may also lose Japanese nationality, with retroactive effect to their birth, potentially invalidating their passports and making them illegally present in Japan.
- They may face criminal penalties in Japan for falsifying information in their passport application, family registry filings, and other government filings based upon their Japanese nationality.
Many individuals in this situation are eligible to naturalize in Japan and restore their Japanese nationality, but this would not solve the other potential legal problems arising from claiming Japanese nationality while they did not legally have it.