France uses a rolling annual census. A person is counted as Iran-born based on:

• Country of birth — "Dans quel pays êtes-vous né(e)?"

French law (Loi Informatique et Libertés, Art. 8) prohibits collecting ethnicity or ancestry statistics, so French-born children of Iran-born parents are not separately identified. INSEE’s detailed country-of-birth tables are also released with a multi-year delay, so 2019 is the most recent Iran-specific figure currently published.