The real downsides of dual citizenship are concentrated, not universal, and they fall unevenly depending on which two countries you hold. Five matter in practice: tax (overwhelmingly a United States problem, because the US taxes its citizens on worldwide income wherever they live, while almost every other country taxes on residence); compulsory military or national service in a handful of countries; nations that prohibit dual nationality outright and force a choice; a ceiling on consular protection known as the master nationality rule; and banking, reporting and cross-border succession friction. For most people whose two countries both allow dual nationality, and who are not US persons, these downsides are manageable with planning, and the added mobility and security usually outweigh them.
This guide weighs each downside against who it actually affects, with named government sources for every figure. For the other side of the ledger, see our companion piece on the countries that allow dual citizenship in 2026.
Key Takeaways
- Tax is mostly a US issue: the United States taxes citizens on worldwide income regardless of residence, while most other countries tax on residence (IRS, 2026).
- Renouncing US citizenship can trigger an exit tax. A "covered expatriate" has net worth of at least USD 2,000,000, or average annual net income tax above USD 206,000 (2025) (IRS, 2025).
- A few countries conscript citizens including dual nationals, among them Greece, Turkey and South Korea, and can bar exit until service is completed (UK FCDO, 2026).
- India, China, Japan and Singapore do not permit dual citizenship; India's OCI card is not Indian citizenship (India Ministry of Home Affairs, 2026).
- Under the master nationality rule, your government generally will not intervene for you against your other country of nationality (US State Department, 2026).
- For most non-US nationals whose two countries both allow it, the downsides are manageable and the optionality often outweighs them.
What are the real downsides of dual citizenship?
The downsides of dual citizenship are real but concentrated, and they fall unevenly. The five that move the needle are tax (overwhelmingly a US-citizen issue, since the US taxes worldwide income regardless of residence per the IRS, 2026), compulsory service, prohibiting countries, the consular ceiling, and reporting friction. Who you are, and which two countries you hold, decides which apply.
Notice what is missing from that list: a universal "double taxation" trap. That fear is the single most repeated claim in citizenship marketing, and for most dual nationals it is overstated. If you hold, say, a British and a Portuguese passport and have no US tie, you are taxed where you are resident, not twice on the same income simply because you hold two passports. The genuine tax burden is concentrated on US persons, which we isolate below.
The honest way to read these downsides is as variables, not constants. A man who gains nationality by descent from a conscripting country faces a service question that never touches a retiree acquiring a second passport elsewhere. Someone naturalising into Singapore faces a renunciation rule that does not apply in the EU. So the right question is not "is dual citizenship bad?" but "which of these five applies to my two specific countries, and how do I plan for it?"
Citation capsule: The downsides of dual citizenship are concentrated rather than universal. They cluster into five areas: US worldwide-income taxation, compulsory military service in some countries, nations that prohibit dual nationality, the master nationality rule limiting consular help, and cross-border reporting friction (IRS, 2026; US State Department, 2026). Which apply depends on the two specific countries you hold.
Do dual citizens pay tax in both countries?
For most dual nationals, no: the United States is the outlier. The US taxes its citizens on worldwide income regardless of where they live, a system called citizenship-based taxation (IRS, 2026). Almost every other country taxes on residence instead, so a non-US dual national is generally taxed where resident, not twice for holding two passports. The double-tax fear is largely a US-person problem.
Why the US is the exception
The US is one of very few countries to tax on citizenship rather than residence. A US citizen living in Dubai or London still files a US return on worldwide income, even with zero US-source income (IRS, 2026). US citizens abroad receive an automatic two-month filing extension to 15 June, but interest still accrues on any tax unpaid by the regular April due date (IRS Publication 54, 2025). Mechanisms such as the foreign earned income exclusion and foreign tax credits often reduce or erase the actual US bill, but the obligation to file does not disappear.
FATCA and FBAR reporting
The reporting layer is where many US dual nationals feel the weight. An FBAR (FinCEN Form 114) is required if your aggregate foreign accounts exceed USD 10,000 at any point in the year (IRS, 2026). Separately, FATCA Form 8938 applies above higher thresholds, USD 200,000 in foreign assets at year-end for a single filer living abroad, with the in-US threshold lower at USD 50,000 (IRS, 2026). These are filed in addition to each other, not instead of, and the paperwork burden is the part that most surprises accidental Americans.
The exit tax on renouncing US citizenship
Renouncing does not always come free. Giving up US citizenship can trigger the IRC 877A exit tax if you are a "covered expatriate", defined as having a net worth of at least USD 2,000,000, OR an average annual net income tax above USD 206,000 (the 2025 figure), OR failing to certify five years of tax compliance on Form 8854 (IRS, 2025). A covered expatriate is treated as having sold worldwide assets at fair market value the day before expatriation, with a 2025 mark-to-market gain exclusion of USD 890,000 (IRS Form 8854 instructions, 2025). Model this before acting, not after.
So the practical rule is this. If you are, or are about to become, a US person, model the tax and reporting cost first, ideally before you acquire or renounce anything. If you are not a US person and your two countries both tax on residence, the double-tax scare rarely matches reality. For the UK's residence-based treatment specifically, see our note on dual citizenship and the UK in 2026.
Citation capsule: The United States taxes citizens on worldwide income regardless of residence, requiring filing abroad plus FBAR and FATCA reporting, and renouncing can trigger an exit tax for a covered expatriate with net worth of at least USD 2,000,000 or average annual net income tax above USD 206,000 in 2025 (IRS, 2025). Most other countries tax on residence instead.
Can dual citizens be forced to do military service?
Yes, in a small number of countries, and the obligation can apply to dual nationals. The US State Department warns that a dual national may have to perform military service in their other country of nationality, an obligation that can be imposed on arrival or departure (US State Department, 2026). It typically affects men, often those who gained nationality by descent, and bites hardest if they travel to or reside in the conscripting country.
Greece, Turkey and South Korea
Greece illustrates the exit-ban risk most clearly. Men aged 19 and over who were born to a Greek national may have military service obligations regardless of any other nationality, and can be stopped from leaving Greece until they complete or formally defer service (UK FCDO, 2026). Turkey applies conscription to its male citizens including dual nationals (UK Home Office, 2025). South Korea also maintains conscription that can reach male dual nationals, a point the US State Department (2026) flags in its general dual-nationality guidance.
Israel, Singapore and the exit-ban trap
Some cases are best stated cautiously. Compulsory service is widely understood to apply to citizens including reportedly Israel, though the precise treatment of dual nationals depends on individual status and is worth confirming with the relevant authority. Singapore enforces National Service for male citizens, and men with outstanding National Service obligations may be refused renunciation of citizenship (ICA Singapore, 2026). The recurring trap across these countries is the exit ban: the obligation often becomes enforceable precisely when you enter the country, and can prevent you leaving until it is resolved.
Citation capsule: A dual national may have to perform military service in their other country of nationality, imposed on arrival or departure (US State Department, 2026). In Greece, men aged 19 and over born to a Greek national can be barred from leaving until service is completed or deferred (UK FCDO, 2026). Turkey conscripts male citizens including dual nationals.
Which countries do not allow dual citizenship?
Several major countries prohibit or tightly restrict dual citizenship, forcing a choice rather than allowing both. India does not permit it at all, and its widely held OCI card is explicitly the status of a foreign national, not Indian citizenship (India Ministry of Home Affairs, 2026). China and Japan also restrict it, while Austria is generally restricted, with exceptions. The cost here is renunciation or automatic loss, not tax.
India: OCI is not citizenship
This distinction trips people up constantly. India does not allow dual citizenship, and the Overseas Citizen of India card, despite its name, makes the holder a foreign national with certain residency and entry rights, not an Indian citizen (India Ministry of Home Affairs, 2026). OCI is a long-term substitute, not a second nationality. If you naturalise elsewhere, you give up Indian citizenship; OCI lets you keep deep ties to India, but it is not the same legal thing.
China, Japan and the choice rule
China does not recognise dual nationality, and a Chinese national who voluntarily acquires foreign citizenship automatically loses Chinese citizenship under Articles 3 and 9 of its Nationality Law (National Immigration Administration of the PRC, 2026). Japan requires a person who holds more than one nationality to choose one by a prescribed deadline; choosing Japanese means renouncing the foreign nationality, and failing to choose can put the Japanese nationality at risk (Japan Ministry of Justice, 2026). Both systems treat dual nationality as a temporary state to be resolved, not a permanent option.
Singapore and Austria
Singapore does not allow dual citizenship: new citizens must renounce their prior nationality, and males with outstanding National Service obligations may be refused renunciation of Singaporean citizenship (ICA Singapore, 2026). Austria is generally restricted, with exceptions; retaining a prior nationality on naturalisation, or keeping Austrian nationality after acquiring another, is possible only in defined cases, so anyone planning around it should confirm their specific route with the Austrian authorities before relying on it.
Citation capsule: India does not permit dual citizenship, and its OCI card confers the status of a foreign national, not Indian citizenship (India Ministry of Home Affairs, 2026). China imposes automatic loss of citizenship on acquiring a foreign one (PRC National Immigration Administration, 2026), Japan requires a choice, and Singapore requires renunciation of the prior nationality.
What is the master nationality rule, and does dual citizenship limit embassy help?
Yes, dual citizenship has a real ceiling on consular protection, set by the master nationality rule. The US State Department explains that local authorities may decline to recognise your US nationality if you are also their national, and US consular officials may be denied access to you, especially if you did not enter on your US passport (US State Department, 2026). Your second country can treat you as solely its own.
How it works in practice
The principle is old but practical. When you are in a country where you hold nationality, that country generally treats you as its citizen first and may not accept that another government has standing to intervene on your behalf. The UK puts it plainly: the FCDO will "not normally" provide consular support to a dual national in the country of their other nationality, with only limited exceptions (UK FCDO, 2026). So the protection you might rely on elsewhere can thin out precisely where one of your nationalities is "home".
What this means for you
Treat it as a planning point, not a reason to avoid a second passport. The risk is real but bounded: it mainly affects you while you are physically in your other country of nationality and need diplomatic help from your first country's mission. For most dual nationals travelling, working or investing in third countries, full consular protection from both governments remains available. The lesson is to know which passport carries which protection, and where, before a problem arises.
Citation capsule: Under the master nationality rule, a country where you hold nationality may decline to recognise your other nationality, and may deny your other government's consular officials access to you (US State Department, 2026). The UK FCDO confirms it will "not normally" assist a dual national in their other country of nationality (UK FCDO, 2026).
How does dual citizenship affect banking, reporting and succession?
Holding ties to two countries adds reporting and cross-border friction, though it is administrative rather than punitive for most. Under the OECD Common Reporting Standard, financial institutions collect every account holder's tax residences and automatically exchange account information across jurisdictions each year (OECD, 2025). That removes old assumptions of banking secrecy and adds know-your-customer questions for cross-border clients, including some dual nationals.
Banking and CRS friction
The friction is real but manageable. CRS means your bank reports your accounts to the tax authorities of every country where you are tax-resident, and some banks "de-risk" by declining clients whose profiles span jurisdictions they find costly to service. This is a compliance burden, not a tax in itself, and it is far heavier for US persons because FATCA layers additional US reporting on top. For non-US dual nationals, the main effect is more paperwork and occasional account-opening friction, not double taxation.
Succession and forced heirship
Estates that straddle two legal systems can clash, particularly over forced heirship, where civil-law countries reserve fixed shares for certain heirs. The EU Succession Regulation 650/2012, known as Brussels IV, sets the default applicable law as the deceased's habitual residence at death, but lets a person instead choose the law of a nationality they hold, for deaths on or after 17 August 2015 (EUR-Lex, 2012). Used deliberately, that election can avoid an unwanted forced-heirship outcome; left to default, or mishandled, two systems can pull an estate in different directions.
Citation capsule: Under the OECD Common Reporting Standard, financial institutions collect all of an account holder's tax residences and exchange account data across jurisdictions annually (OECD, 2025). For cross-border estates, the EU Succession Regulation 650/2012 lets a person choose the law of a nationality they hold to govern succession, for deaths on or after 17 August 2015 (EUR-Lex, 2012).
Which passport should a dual citizen travel on?
Use the passport that matches the country you are entering or leaving, because many states expect their own nationals to enter and exit on their passport. The US State Department's guidance underlines why this matters: entering your other country of nationality on a different passport can complicate both that country's treatment of you and your first country's ability to help (US State Department, 2026). The right-passport question is logistical, but it interacts with everything above.
In practice the habit is simple. Enter and leave each country of nationality on that country's passport, and use whichever passport gives the better visa-free access for third countries. This is not a downside so much as a discipline. Getting it wrong can trigger the very service obligations or consular gaps already covered, so it pays to plan your passport use country by country rather than improvise at the border.
Citation capsule: Many countries expect their nationals to enter and exit on that country's passport, and the US State Department notes that using the wrong one can complicate both your treatment locally and your other government's ability to assist (US State Department, 2026). The practical rule is to use each country's passport for that country, and the stronger passport for third countries.
So, is dual citizenship worth it despite the downsides?
For most people whose two countries both allow it, yes: the downsides are manageable and the optionality usually outweighs them. The genuinely heavy burden, worldwide-income taxation and the exit tax, is concentrated on US persons (IRS, 2026). Conscription touches mainly men tied to a few specific countries. The rest, the consular ceiling and reporting friction, are planning points rather than dealbreakers.
The honest framing is that dual citizenship is a portfolio of rights with a few conditions attached, not a trap. The mobility, the right to live, work and own property in two places, and the security hedge of a second home base are concrete and durable. The downsides are specific, knowable in advance, and mostly avoidable with the right structuring. The error is to treat a US-specific tax problem, or a conscription rule that applies to a minority, as a universal verdict on dual nationality.
So weigh, do not fear. Identify which of the five downsides actually applies to your two countries and your own profile, model the cost before you act, and use the right passport in the right place. If you are comparing the cost-benefit of acquiring a second nationality in the first place, our citizenship by investment guide for 2026 sets out where the trade-off lands. Because these are tax and legal matters that turn on your exact facts, take qualified, country-specific tax and legal advice before acting on anything here.
Frequently asked questions
Do dual citizens pay taxes in both countries?
Usually no. Most countries tax on residence, so a non-US dual national is generally taxed only where resident, not twice for holding two passports. The United States is the main exception: it taxes citizens on worldwide income regardless of where they live (IRS, 2026). The double-tax fear is concentrated on US persons.
Can dual citizens be forced to do military service?
In some countries, yes. The US State Department warns a dual national may have to serve in their other country of nationality (US State Department, 2026). Greece can bar men born to a Greek national from leaving until service is completed (UK FCDO, 2026). Turkey and South Korea also conscript male citizens including dual nationals.
Which countries do not allow dual citizenship?
India, China, Japan and Singapore are the major examples, and Austria is generally restricted with exceptions. India's OCI card is not Indian citizenship (India Ministry of Home Affairs, 2026). China imposes automatic loss of citizenship on acquiring a foreign one (PRC National Immigration Administration, 2026), and Japan requires you to choose one nationality.
Does dual citizenship affect embassy help abroad?
Yes, in your other country of nationality. Under the master nationality rule, the UK FCDO will "not normally" assist a dual national in the country of their other nationality (UK FCDO, 2026), and US consular officials may be denied access (US State Department, 2026). In third countries, protection from both governments generally remains available.
Can I lose my first citizenship if I get a second passport?
It depends on your first country. Some nations impose automatic loss: a Chinese national who voluntarily acquires foreign citizenship loses Chinese citizenship under Articles 3 and 9 of its Nationality Law (PRC National Immigration Administration, 2026). Others, including the UK, the US and many EU states, generally let you keep both. Always confirm your specific country's rule first.
Ready to weigh a second nationality against your own tax, family and mobility position? Explore Ancova's citizenship and residency solutions for a structured view of which route, and which downsides, actually apply to you. This article is general information, not advice; take qualified, country-specific tax and legal advice before acting.
Written by
Amine Derag
Director of Strategy, Ancova Associates
Amine Derag is Director of Strategy at Ancova Associates, the Dubai advisory firm for company formation, residency, citizenship by investment, and cross-border tax structuring. He advises founders and private clients relocating to the UAE on how a UAE structure interacts with their home-country tax and reporting obligations.
Connect on LinkedInThis article is general information for educational purposes only and is not legal, tax, financial, or immigration advice. Investment thresholds, processing times, and program terms change — speak with a qualified Ancova adviser before acting.
