The full nationality law is defined in Book 2 of the Civil Code of Iran, Articles 976 through 991.

[4] An application for naturalisation must be submitted to either directly to the Ministry of Foreign Affairs, or through the Governors, or the Governors-General and must contain certified copies of identity documents in relation to the applicant and his family (wife and children), a certificate certifying the period of residence, a clean criminal record, sufficient property, and employment that ensures a livelihood.

[6] Nevertheless, article 977 of the Civil Code of Iran deals with multiple citizenship.

If they wish to retain the non-Iranian nationality after age 18, they have to inform Iran's Ministry of Foreign Affairs.

[7] In theory, voluntary renunciation of Iranian citizenship is possible for persons over the age of 25, subject to approval by the Council of Ministers.