Can I apply for German citizenship if my grandfather was German?

A German grandparent is the most common starting point we see, and the honest answer to the question is: it depends, and it depends on things you can check. German nationality passes by descent under § 4 StAG, but historical restrictions on who could pass it on, and rules that caused people to lose it, decide most cases.

How transmission used to work

German nationality law was, for most of the twentieth century, restrictive in ways that fall unevenly on families:

• Before 1 January 1975, a child born in wedlock to a German mother and a foreign father did not acquire German citizenship from the mother. If your German ancestor is a grandmother and your parent was born before that date, descent alone will not carry the claim.
• Before 1 July 1993, a child born outside marriage to a German father did not acquire citizenship from him unless paternity was established and further conditions were met.
• Before 1 April 1953, a German woman lost her own citizenship by marrying a foreign national.

These rules were later recognized as discriminatory. Recognizing them as unjust did not retroactively make the descendants German by birth, which is why the 2021 reform created separate routes for exactly these families.

The question that decides more cases: loss

Before asking whether your grandparent could pass citizenship on, ask whether they still had it. This is the step most people skip.

• Ten years abroad, before 1914. Under § 21 of the 1870 act, a German who spent ten uninterrupted years abroad lost citizenship; registration in the consular register interrupted that period. The provision was repealed with effect from 1914.
• Naturalization abroad. For long periods, acquiring another nationality on application caused automatic loss. The decisive fact is the date: a naturalization one year before your parent's birth ends the line, and one year after it does not.
• The generation cut, § 4 (4) StAG. Relevant to the youngest generation: a child born abroad does not acquire citizenship at birth where the German parent was also born abroad after 31 December 1999 and lives abroad, unless the birth is reported to a German mission within one year.

The routes created in 2021

Where an exclusion was caused by the old gender or marital-status rules, § 5 StAG allows acquisition by declaration. It is not discretionary, and it expires: the declaration has to be made by 19 August 2031.

Where the exclusion or loss was connected to Nazi persecution, Article 116 (2) of the Basic Law applies if there was a formal deprivation between 1933 and 1945, and § 15 StAG applies to persecution-related losses that were not formal deprivations.

What to gather before anyone can tell you anything

• Your German ancestor's birth or baptismal record, and the place, not just the country.
• The approximate year they left Germany, and the ship or port if you have it.
• Any naturalization document, or your reason for believing there is none.
• Birth and marriage records for each generation between them and you.
• Anything that suggests contact with a German consulate: a passport, a registration, a stamped letter.

With those in hand, the analysis is a legal one and it is done case by case. Anyone who tells you the answer from the sentence “my grandfather was German” alone is guessing.