Dual Citizenship Obligations
A second passport opens doors. It also opens filing requirements, military service obligations, and tax liabilities that you might not know about until a border agent or tax authority brings them up.
Taxes
The US is the most extreme case. American citizens owe federal income tax on worldwide income regardless of where they live. If you're a US citizen living in Berlin earning a salary from a German employer, you file with both the IRS and the German tax authorities. Tax treaties and the Foreign Earned Income Exclusion ($126,500 for 2024) reduce or eliminate double taxation in most cases, but the filing obligation never goes away.
US citizens abroad must also report foreign financial assets. FATCA (Form 8938) requires disclosure if foreign financial assets exceed $200,000 on the last day of the tax year (or $300,000 at any time) for individuals living abroad. FBAR reporting through FinCEN kicks in at $10,000 in aggregate foreign account balances. Penalties for non-filing start at $10,000 per year.
Most other countries tax based on residency, not citizenship. If you're a French citizen living in Canada, France doesn't tax your Canadian income. But if you're a US-French dual citizen living in Canada, the US still wants its paperwork. Eritrea is the other notable exception, charging a 2% diaspora tax on citizens abroad.
Military service
Several countries have mandatory military service that applies to dual citizens.
South Korea: Male citizens must complete 18-21 months of service. Dual citizens must choose their nationality by the end of March the year they turn 18. Those living abroad continuously can defer until age 37, but the obligation remains.
Israel: All citizens, including dual nationals, are subject to conscription at age 18. Men serve approximately 32 months, women 24 months. Citizens abroad must register their military status between ages 16 and 19 through an embassy or consulate.
Turkey: All male citizens under 45 are subject to service, including dual citizens who acquired citizenship before age 22. Those who naturalized after 22 are exempt. A paid exemption (buyout) option is available.
Greece: Male citizens must complete 12 months of service. Dual citizens living abroad can apply for postponement.
Passport usage
Most countries require you to enter and exit on that country's passport. If you're a dual citizen of Country A and Country B, you enter Country A on your A passport and Country B on your B passport. Using the wrong one can create complications with border agents, mismatched entry/exit records, and denied boarding by airlines.
Always present the passport of the country you're entering.
Voting
Some countries make voting mandatory, and the obligation extends to citizens abroad.
- Australia: Enrolled citizens must vote in federal elections. The fine for not voting without a valid reason is AUD 20, but failure to respond can escalate to court proceedings.
- Brazil: Voting is mandatory for citizens aged 18-70. Citizens abroad must vote at their nearest consulate or justify their absence. Non-compliance can result in restrictions on obtaining a passport, public employment, or government loans.
Even where voting is voluntary, dual citizens may have voting rights in both countries. Whether exercising both is legal depends on the specific laws involved.
Reporting requirements
Some countries require citizens to notify authorities when they acquire a second nationality. Consequences for non-reporting range from fines to, in rare cases, loss of the original citizenship. Check both countries' requirements before and after acquiring a second passport.
Countries that restrict dual citizenship
Not all countries allow it.
- China: Acquiring foreign citizenship results in automatic loss of Chinese citizenship under the Nationality Law.
- India: Does not allow dual citizenship. Offers Overseas Citizenship of India (OCI) instead, which provides residency and travel rights but is not full citizenship.
- Japan: Technically requires citizens to choose one nationality by age 22. Enforcement is minimal in practice.
- UAE, Saudi Arabia, Singapore, Indonesia: All restrict or prohibit dual citizenship in various forms.
People who acquire citizenship by descent sometimes discover obligations they didn't expect. If a parent registered you as a citizen of their home country at birth, you may have military service requirements, tax obligations, or reporting duties you've never been informed about.