The early seventeenth century was critical period of transition for the Ottoman Empire, in which a series of internal and external crises shook its institutional foundations. Strongly affected were the sultan’s household troops (kapıkulları), which developed beyond their role as a standing army, multiplying in number and taking on a variety of new official and unofficial functions. While much scholarly attention has been directed to the famous janissary infantry, this paper addresses the lesser-studied cavalry branch, called “the people of the six regiments” (altı bölük halkı). A highly dynamic organization, the cavalry increasingly took on administrative roles and, in conjunction with several rebellions in the capital, were able to consolidate a near-monopoly over tax-collection positions in the central provinces of the empire. The cavalry’s preeminence in this function reached its apogee following the regicide of Sultan Osman II (r. 1618-22) and continued thereafter until 1632. At that point, the reformist government of Sultan Murad IV (r. 1623-40) declared them to be usurpers and acted to curtail their privileged status in administration. At present, our knowledge of this episode in Ottoman history is dependent on the reports of later chroniclers and on declarations issued by the government of Murad IV. These sources portray the period as an aberration, in which the empire’s norms were temporarily and violently disrupted by thuggish cavalrymen intent on seizing control over the taxation apparatus. In order to complicate this portrayal, this paper approaches the period from the perspective of contemporary bureaucratic records preserved in the Ottoman Archives in Istanbul. A documentary investigation reveals the functioning of the institution by which the cavalry’s administrative role was established and perpetuated, referred by the term mülazemet. When the image of “usurpation” is subjected to critique, it becomes apparent that this represents only one of many contemporary points of view. The emergence and subsequent reaction against the cavalry’s predominance in tax collection should be understood as part and parcel of contemporary debates over the proper role of the household troops in Ottoman state and society.