FlagSageWhat this covers
Citizenship by descent, or ius sanguinis, is citizenship that comes from a parent or ancestor who is or was a citizen, rather than from birth in the country or from naturalization. In some countries it exists from birth and an official procedure only confirms it. In others the descendant must register, make a declaration or apply for naturalization on special terms. Countries often limit the number of generations, require registration within a deadline, or require language skills or a real link to the country.
Understand the three ways descent routes work
Descent rules fall into three broad groups. In the first, citizenship exists automatically from birth, and the descendant asks the state to confirm or recognize it. Poland's confirmation procedure and Germany's determination procedure work this way. In the second, the descendant becomes a citizen only after registering or declaring, as with Ireland's Foreign Births Register and Portugal's route for grandchildren. In the third, the descendant applies for naturalization on easier terms, as with Hungary's simplified naturalization.
The difference matters. A confirmed citizen by birth may already carry duties, such as US-style citizenship taxation in the rare countries that use it, or military service. A person who registers or naturalizes becomes a citizen only from the date the law sets.
See the citizenship by descent and naturalization entries, and second citizenship basics for the wider picture.
Compare descent rules in six countries
The table summarizes what official pages and legislation said when checked. Each route has further conditions, and the law in force on the dates of each relevant birth can matter.
| Country | Type of route | Main limit or condition | Who handles it |
|---|---|---|---|
| Italy | Recognition of citizenship from birth | Since Decree-Law 36/2025, people born abroad with another citizenship qualify only if a parent or grandparent held exclusively Italian citizenship, a parent lived in Italy for two continuous years before the birth, or an application was filed by 23:59 Rome time on 27 March 2025 | Italian consulates, municipalities or courts |
| Ireland | Registration in the Foreign Births Register | A person born abroad with a grandparent born in Ireland, or with a parent who was an Irish citizen at the time of the birth but not born in Ireland, can register. Citizenship starts on entry in the register. | Department of Foreign Affairs |
| Poland | Confirmation of existing citizenship | Proof of the Polish citizenship of parents or grandparents, such as civil and church records and old Polish documents | Provincial governor (voivode), through a consulate when abroad |
| Germany | Determination of existing citizenship | A child of a German parent acquires citizenship at birth, but a child born abroad to a German parent who was also born abroad after 31 December 1999 does not, unless the birth is registered within one year | Federal Office of Administration (BVA) for people abroad |
| Hungary | Simplified naturalization | An ancestor who was a Hungarian citizen or is likely of Hungarian origin, plus Hungarian language skills checked by the authority | Hungarian consulates and government offices |
| Portugal | Declaration for grandchildren of Portuguese citizens | A grandparent who was Portuguese by origin and did not lose that nationality. Since Organic Law 1/2026, applicants must also meet language, civic and security conditions | Central Registry Office in Lisbon |
Check Italy's rules after the 2025 reform
Italy used to allow citizenship to pass by descent without a generational limit. Decree-Law 36 of 28 March 2025, converted into law by Law 74/2025, changed that. The Italian Constitutional Court's press office summarizes the rule: a person born abroad, even before the decree took effect, who holds another citizenship is considered never to have acquired Italian citizenship.
There are three exceptions. Citizenship is still recognized if the application was filed, administratively or in court, by 23:59 Rome time on 27 March 2025. It is recognized if a parent or grandparent holds, or held at death, exclusively Italian citizenship. And it is recognized if a parent or adoptive parent lived in Italy for at least two continuous years after acquiring Italian citizenship and before the child's birth or adoption.
In practice the reform limits descent claims for people with another nationality to one or two generations, and only where that parent or grandparent was not also a citizen of another country. On 12 March 2026 the Constitutional Court announced that it had rejected, as partly unfounded and partly inadmissible, challenges to the rule raised by the Turin court. Separate rules let some minor children acquire citizenship by a parental declaration. Italian consular pages give different deadlines for those declarations, so check with the consulate that covers you. See Italy.
Check the routes in Ireland, Poland, Germany, Hungary and Portugal
Ireland. A person born abroad is an Irish citizen automatically if a parent was born in Ireland. A person with a grandparent born in Ireland, or with an Irish citizen parent who was not born in Ireland, can become a citizen by registering in the Foreign Births Register, and citizenship starts from the date of entry. See Ireland.
Poland. The Polish embassy in the United States says a person without documents confirming Polish citizenship can ask the provincial governor, through a consulate, to confirm it. Applicants submit records that confirm the Polish origin of their parents or grandparents. The embassy lists a fee of US$118. See Poland.
Germany. Section 4(1) of the Nationality Act gives German citizenship at birth to a child with a German parent. Section 4(4) adds a generational cut-off for children born abroad to a German parent who was born abroad after 31 December 1999 and lives abroad, unless the birth is registered within one year or the child would otherwise be stateless. The Federal Office of Administration confirms citizenship for people abroad and issues a certificate of nationality. The Federal Foreign Office says victims of Nazi persecution who were deprived of citizenship and their descendants have a separate entitlement to restoration under Article 116(2) of the Basic Law or Section 15 of the Nationality Act. See Germany.
Hungary. Hungarian embassies say a person whose ancestor was a Hungarian citizen, or is likely to be of Hungarian origin, can apply for simplified naturalization if they also show knowledge of Hungarian. The embassy in The Hague stresses that no statutory exemption excuses a lack of language skills and that the authority checks it directly. See Hungary.
Portugal. A person born abroad with a grandparent who was Portuguese by origin and did not lose that nationality can declare that they want to be Portuguese. The Portuguese consulate in Newark says the claim is handled by the Central Registry Office in Lisbon and that an effective connection to the community is presumed with sufficient knowledge of Portuguese. Organic Law 1/2026 of 18 May 2026 now makes this route depend on the conditions in Article 6(1)(c) to (h) of the Nationality Law, including a test of Portuguese language and culture. See Portugal.
Gather the documents most descent claims need
Every country asks you to prove each link in the chain between you and the ancestor, not only the ancestor's citizenship. Hungary's embassy says the line of descent must be clear and that intermediate ancestors must also be documented. Germany's BVA says you may need an ancestor's passport documents and asks for certified copies.
Expect long lead times. Records may sit in civil registries, church archives or national archives in more than one country, and names are often spelled differently across documents.
- Full birth certificates for you and each generation back to the ancestor, showing parents' names
- Marriage, divorce, name-change and death certificates that connect the generations
- Proof of the ancestor's citizenship, such as a passport, ID card, registry entry or military record
- Proof of whether the ancestor kept or lost that citizenship, for example by naturalizing elsewhere, and when
- Apostilles or consular legalization, and certified translations into the language the authority requires
- Criminal record certificates where the route requires them, as Portugal's does
Plan for what changes after citizenship is confirmed
A new citizenship can bring duties as well as a passport. Check whether either country restricts dual citizenship, whether military service applies to citizens abroad, and how you would pass citizenship to your own children under the generational limits above.
Citizenship by descent does not move your tax residence, which follows where you live. The reverse case also exists. A person who learns they are a US citizen by descent is under the same US filing rules as other US citizens abroad. See US citizens abroad and accidental Americans. EU citizenship gained through descent also gives the right to live and work in other EU countries, which is a living base question as much as a citizenship one.
Common misconceptions
Questions to take to a professional
- Which law applied on the date of each birth in my line, and did any ancestor lose citizenship before the next generation was born?
- Does my country of descent recognize citizenship from birth, or do I need to register, declare or naturalize?
- Did any parent or grandparent in my line hold another citizenship, and does that matter under the current rules?
- Which records do I need from which countries, and how must they be legalized and translated?
- Does either of my countries restrict dual citizenship or impose military service on citizens abroad?
- Could I pass the citizenship on to my own children under the generational limits?
- Would confirming this citizenship create any tax or reporting duties for me?
Questions people ask
Can I still get Italian citizenship through my great-grandparents?
Since Decree-Law 36/2025, a person born abroad with another citizenship qualifies only if a parent or grandparent held exclusively Italian citizenship, a parent lived in Italy for two continuous years before the birth, or an application was filed by 27 March 2025. Claims through great-grandparents generally fall outside those exceptions.
Did the Italian Constitutional Court strike down the 2025 citizenship decree?
No. On 12 March 2026 the Court announced that it had declared the Turin court's challenges partly unfounded and partly inadmissible. Other challenges may follow, so check the current position.
Can I get Irish citizenship through a grandparent?
Yes, if the grandparent was born in Ireland. The person registers in the Foreign Births Register and becomes an Irish citizen from the date of entry. Check the Department of Foreign Affairs for current documents and fees.
Can I get German citizenship by descent?
A child of a German parent generally acquires citizenship at birth, but a generational cut-off applies to children born abroad to German parents also born abroad after 1999, unless the birth is registered within a year. Descendants of people deprived of citizenship by the Nazi regime have a separate restoration route.
Do I need to speak the language to get citizenship by descent?
It depends on the route. Hungary's simplified naturalization requires Hungarian, and Portugal's grandchild route now includes a language and culture test. Confirmation routes such as Poland's focus on documents instead.
What documents do I need for citizenship by descent?
Usually full birth, marriage and death records linking each generation, proof of the ancestor's citizenship and of whether it was lost, plus apostilles and certified translations. Each authority publishes its own list.
Where this guide stops. A consulate, a central civil registry or a national nationality authority decides or confirms each claim, and in some countries a court can rule on disputed cases. A nationality lawyer or a genealogist can help trace and document a line of descent. FlagSage does not assess family trees, order records, or prepare applications.
Sources
- Comunicato del 12 marzo 2026: la Corte costituzionale respinge le questioni relative al decreto-legge 36/2025 (Corte costituzionale)Primary law
- Cittadinanza (Consolato Generale d'Italia a New York)Official guidance
- Modifiche alla normativa sulla cittadinanza italiana (Consolato d'Italia a Curitiba)Official guidance
- Registering a foreign birth (Department of Foreign Affairs, Ireland)Official guidance
- Confirming Polish citizenship or its loss (Embassy of Poland in the US, gov.pl)Official guidance
- Staatsangehörigkeitsgesetz (StAG) § 4Primary law
- Feststellung der deutschen Staatsangehörigkeit (Bundesverwaltungsamt)Official guidance
- Law on Nationality (Federal Foreign Office, Germany)Official guidance
- Simplified naturalization (Embassy of Hungary in The Hague)Official guidance
- Nacionalidade para Netos de Avós Portugueses (Consulado Geral de Portugal em Newark)Official guidance
- Lei Orgânica n.º 1/2026, de 18 de maio (Diário da República)Primary law
- U.S. citizens and residents abroad: Filing requirements (IRS)Official guidance
Related
- Countries covered
- Italy, Ireland, Poland, Germany, Hungary, Portugal, United States
- Sources
- 12 sources listed above
- Tax year
- Current rules as checked
- Review
- Not professionally reviewed
Sources checked November 9, 2026