When did Mamdani become a citizen?

The official Assembly biography says Mamdani became naturalised as an American citizen in 2018.

A precise day is not needed for the public city record unless a legal filing or official document puts it in issue. The important public fact is naturalisation before his Assembly service and before his mayoral election.

For mayoral office, naturalised citizenship is not a barrier.

The date gets searched because people connect it to eligibility. For New York City mayor, the governing issue is citizenship and election to office. For president, the natural born citizen clause is the separate legal issue.

That is why the year 2018 matters for biography, while the constitutional question matters for national office.

Use the official Assembly biography for the public year. Use the president eligibility page for the national office question.