A Grand Ayatollah who has attained recognition as a marja-e taqlid, source of emulation, holds the most senior level of religious authority within Twelver Shia Islam, a status achieved through advanced seminary study culminating in ijtihad, the qualified capacity for independent legal reasoning from Islamic sources, and, crucially, through recognition by the existing community of senior scholars and, ultimately, by the ordinary believers who choose to follow that scholar's specific legal rulings on matters of religious practice, since Twelver Shia practice generally requires an adherent to follow, taqlid, the rulings of a living marja rather than reasoning independently from primary sources without the necessary scholarly qualification. Multiple Grand Ayatollahs typically hold marja status simultaneously, each maintaining his own following and his own risalah, a comprehensive practical manual of religious law addressing everyday questions from ritual purity to financial transactions, so that Twelver Shia religious authority is genuinely plural rather than concentrated in a single office.
Followers of a given marja traditionally pay khums, a religious tax of one-fifth on certain categories of income, directly to their chosen marja's office, which uses the funds to support seminary students, charitable works and the maintenance of religious institutions, a financial relationship that gives a prominent marja's office substantial independent resources and, correspondingly, real institutional weight beyond purely scholarly influence.