"According to the dhimma status system, non-Muslims must pay a poll tax in return for Muslim protection and the privilege of living in Muslim territory. Per this system, non-Muslims are exempt from military service, but they are excluded from occupying high positions that involve dealing with high state interests, like being the president or prime minister of the country. In Islamic history, non-Muslims did occupy high positions, especially in matters that related to fiscal policies or tax collection".
Abou El Fadl, Khaled (2007). The Great Theft: Wrestling Islam from the Extremists. HarperOne. p. 204. ISBN 978-0061189036.