A characteristic element of Ottoman early modernity is the growing influence of money in imperial politics. In the seventeenth century, not only was the economy itself becoming increasingly monetized, but the rising cost of warfare forced statesmen to find creative new ways of generating revenue. In the 1640s and 1650s, acute budget deficits led the empire into a full-blown fiscal crisis, as the empire struggled to keep the army paid and the navy in operation. To meet these expenses without increasing the tax burden, successive grand viziers resorted to deficit financing: they borrowed enormous sums from financiers, whom they reimbursed by promising payment from the tax revenues of future years. The financers who provided these loans won great influence at court, but they have yet to be closely studied by today's scholars. This study uses documentary evidence from the Ottoman Archives (BOA) to examine the career of the most prolific of the mid-century financiers, Gümrük Emini (‘Customs Officer’) Hasan Agha, an Armenian convert to Islam and Istanbul’s customs officer from 1646 to 1656. A microhistorical approach to Hasan Agha’s career sheds light on his success as a financier, which depended on the skills and connections through which he raised credit for his loans as well as the careful strategizing that enabled him to survive the exceptionally volatile politics of his era—until his sudden downfall in 1656.