This paper is a study of the concept of zakat in the thought of the fifth/eleventh century Fatimid Ismaili missionary and philosopher, Nasir-i Khusraw (d. ca. 1088). The study is based on Nasir-i Khusraw’s famous work called “The Face of Religion” (wajh-i din), in which he offers a spiritual exegesis of all the ritual pillars of Islam in summary and in detail in accordance with the principles of Ismaili cosmology and theology. Khusraw’s exegesis of zakat is noteworthy for three reasons: first, he interprets zakat as neither charitable alms nor a religious tax paid to a Caliph; rather, he situates zakat as primarily being a “purification payment” which the Prophet would accept from believers to cleanse their souls and which every Fatimid Ismaili Imam-Caliph continues to do as Muhammad's heirs. This interpretation of zakat as different from charitable alms matches the findings of Suliman Bashear and Fred Donner, who made this argument on the basis of the Qur’an and specimens of Sunni tafsir. It is also echoed in Twelver Shii hadith literature on the topic. Second, Khusraw presents zakat as a kind of “religious capital” whose signified reality consists of “spiritual capital” – this spiritual capital being divine inspiration or ta’yid which God continuously provides to the cosmic, natural, and religious hierarchies. In other words, the material flow of zakat among the believers is an allusion to the spiritual flow of divine inspiration. Thirdly, Khusraw provides a highly detailed exegesis of specific zakat rates on gold, silver, animals, plants etc. This means that particular animals like sheep, cattle, and camels symbolize the Prophet and the Imams. The overall thrust of Khusraw’s spiritual exegesis of zakat is to re-orient the Ismaili practitioner from the worldly, material dimension of zakat to its spiritual and cosmic realities.