Tarasios was born and raised in the city of Constantinople. A son of a high-ranking judge, Tarasios was related to important families, including that of the later Patriarch Photios the Great. Tarasios had embarked on a career in the secular administration and had attained the rank of senator, eventually becoming imperial secretary ("asekretis") to the Emperor Constantine VI and his mother, the Empress Irene. Originally he embraced Iconoclasm, but later repented, resigned his post, and retired to a monastery, taking the Great Schema (monastic habit).