Citizenship by descent: which passport can your family give you?

Nationality laws ask one question at every link of a family line: was the parent a citizen on the day the child was born? If yes, the child was born a citizen too, often without any paper ever being filed, and the chain goes on. If the parent had already lost that citizenship, the chain breaks at that point and nothing below it can be rebuilt by descent.

The most common break in American families is naturalization. Until the second half of the twentieth century, many European countries withdrew their citizenship from anyone who voluntarily took another. An Italian emigrant who became a US citizen in 1920 lost Italian citizenship that year; a son born in 1918 was born Italian, a daughter born in 1922 was not. A German emigrant who naturalized in 1925 lost German citizenship the same way. This is why the checker asks for the year the ancestor naturalized, and compares it with the birth year of the next child in the line.

The second break is the mother. Many laws let only a father pass on citizenship to a child born in wedlock until a date set by a reform or a court: 1948 in Italy, 1975 in Germany, 1983 in the United Kingdom, 1984 in Greece. Some countries later repaired those cases with a declaration; others did not, or only through a court. A line that runs through a woman therefore needs her children's birth years. The third limit is the number of generations born abroad: Italy now stops at the grandparent, the United Kingdom at the parent, Ireland at the grandparent born on the island, while Poland, Germany or Greece set no generation limit as long as every link held.

Several of the routes Americans used most were rewritten in less than two years, which makes older guides wrong for at least one country in every family.

• Italy. Decree-Law 36/2025, converted by Law 74/2025, added article 3-bis to the 1992 citizenship law with effect from March 28, 2025 (Normattiva). A person born abroad who holds another citizenship is treated as never having been Italian, unless the case was filed by March 27, 2025, or a parent or grandparent held only Italian citizenship, or a parent lived in Italy for two years before the birth. Details on the Italian citizenship page.
• Canada. Bill C-3 came into force on December 15, 2025 (IRCC). It removed the first-generation limit for people born abroad before that date, and set a test of 1,095 days of physical presence in Canada for a Canadian parent born abroad whose child is born later. See Canadian citizenship by descent.
• Spain. The Democratic Memory Law option for grandchildren of exiles and emigrants closed on October 22, 2025 (Spanish consulate); files lodged in time are still being decided. See Spanish citizenship by descent.
• Portugal. Organic Law 1/2026 added a language and culture requirement for grandchildren from May 19, 2026 (Diário da República). See Portuguese citizenship by descent.
• Germany. Since June 27, 2024 Germany accepts multiple citizenship and no longer withdraws it from Germans who naturalize abroad (Federal Office of Administration). The free declaration for children of German mothers and of unmarried German fathers, section 5 of the Nationality Act, stays open until August 19, 2031 (StAG s. 5). See German citizenship by descent.

Whatever the country, the file proves the same chain: the ancestor's birth abroad, then each birth and marriage down to you, then the date the ancestor became a US citizen, or proof that they never did. Most of that paper is American.

Vital records come from the state where each event happened, as certified long-form copies. Fees are set by each state: California charges $31 for a birth record, $19 for a marriage and $26 for a death since January 1, 2026 (California Department of Public Health).

Naturalization records show the date that decides the line. Court records held by the National Archives cost $25 a copy (NARA). USCIS holds files opened from 1906 onward and answers through its genealogy program: an index search costs $30 online, a record copy $30 online. When no record exists, Form G-1566 asks USCIS for a certificate of non-existence, at $280 online.

Apostilles make a US record valid abroad. State records get one from the secretary of state of that state; federal records, such as a USCIS letter, get one from the State Department's Office of Authentications at $20 per document, with about 5 weeks by mail (State Department). Ireland, Canada and the United Kingdom ask for no apostille; Italy, Poland and Greece do. The document checklist lists what each country wants and the cost calculator adds the bill for your line.

US law does not ask you to choose. A US citizen may acquire another nationality by birth, descent or naturalization without asking any US authority (State Department), and citizenship is lost only through a voluntary act done with the intention of giving it up (8 U.S.C. 1481). Recognition by descent is not even an act of naturalization: the other country confirms a status it says you have held since birth. Two duties remain. You enter and leave the United States on your US passport, and you keep filing US tax returns on your worldwide income.

A second passport does not change your taxes; foreign accounts do. If the total of your foreign accounts passes $10,000 at any moment of the year, you file an FBAR with the Treasury (IRS), and Form 8938 applies above higher thresholds. Living and working abroad opens the foreign earned income exclusion. The tax page for dual citizens runs each test, and the page on dual citizenship for Americans covers the passport rule and loss of nationality. Whether you keep the other citizenship is a question for the other country: the table of countries shows which ones set conditions.

Many American families have three or four foreign-born ancestors from different countries. The checker takes up to three lines at once, so you can compare them side by side. Three questions usually settle the choice.

1. Which line works under today's law? A great-grandparent from Italy no longer counts for a new file, while a great-grandparent from Poland or Germany may, if nobody in between lost citizenship first.
2. Which line needs the fewest records? Each generation adds a birth, often a marriage, and sometimes a death record, each with its apostille and translation. A grandparent line costs less than a great-grandparent line, and a country that asks for no apostille costs less again.
3. Which passport serves your plans? Every citizenship of a European Union country gives the right to live and work in all of them, so an Irish, Polish or German passport opens Italy, Spain or France too. A Canadian or British passport opens its own country only.

The second citizenship page ranks the open routes by how far back they reach, and each country page carries its own short tool to test one line in depth.

Most negative answers come from four causes. The emigrant naturalized before the next child in the line was born. A mother passed on citizenship before her country allowed it, with no later repair. The line has more generations born abroad than the country accepts. Or the route itself closed on a known date, as Spain's did in 2025. The checker names the cause and links the law it rests on.

Some facts it cannot judge: adoptions, legitimations and court decisions on parentage, name changes that make records disagree, military service or residence abroad that some old laws treated as a loss, and decisions left to an official's discretion, such as Slovakia's grant or a German naturalization for people born before 1949. When one of these is in play the answer says "possible, to check". Its verdicts are not legal advice: the country concerned decides, and the method page explains each rule and its limits.