Requirements were read on Oct 28, 2026. A cell marked "Not found on an official page" is one we found no official page for, so we leave it empty. France is in the table because it tightened its rules from 1 January 2026, and the list of dated changes has the entries.
What differs from one country to the next
Citizenship takes 5 years in France, Germany and Netherlands and 10 in Spain, Portugal and Italy. The language level asked for citizenship goes from A2 in the Netherlands and in Spain (the DELE exam) up to B2 in France.
The permanent or long-term card has its own rules, often lighter than citizenship. In the Netherlands the same civic integration exam at A2 serves the permanent permit and naturalisation. In France the card asks for B1 and citizenship for B2.
On keeping the US nationality, Spain asks the applicant to renounce the previous nationality and the Dutch IND says a person usually has to. For Portugal, Italy and Germany the law text we read has no such clause. France's cell is empty because the pages we read do not say. This is a reading of the law, not a verdict on a case, and the US side is a separate question that Dual Citizenship France USA: The Complete Guide for Americans Who Naturalize French covers.
Italy and the Netherlands name the EU long-term residence permit in the pages we read, both with 5 years of residence, and Portugal calls it long-term resident status. Each cell says which permit it describes.