Öz The avariz and nüzul levies were among the most important of the regular sources of government revenue in the Ottoman empire during the seventeenth century, but there has been relatively little study of them. Originating in the late fifteenth century as irregular imposts levied at times of military need, it is clear that by the first quarter of the seventeenth century avariz and nüzul had become virtually annual levies throughout the majority of the Rumelian and Anatolian provinces. This article examines the nature of these levies as seen through collection procedures in the province of Karaman in the period 1620 to 1700, showing how the Ottoman financial administration developed this relatively new and lucrative source of income in a consistent and fair manner.