Ever since the late eighteenth century, no subject has been more prominent in histories of ‘the transition to colonialism’ in south Asia, than the issue of taxation. In particular, the complex system of agrarian taxation that was developed under the Mughal empire, and further elaborated by various post-Mughal regimes, has often been seen as the defining institution of both the pre-colonial and colonial states. What the British called ‘land revenues’, which included taxes on land proper (mal) and taxes on trade and markets (sair), were the main source of income for both Indian and British rulers. Assessments of the impact of colonial rule have often depended on supposed changes in the tax regime. Since the nineteenth century historians have tended to focus their attention on the relationship between the land tax and structures of agrarian property. They have generally argued that British rule both substantially increased the tax burden, and modified structures of agrarian tenure by splicing together rights of revenue collection and private property in land. But they have focused much more on early colonial policies with regard to private landed property, and less on the issue of the actual tax assessment. This paper takes up the issue of the land tax demand (known as jama in the terminology of Mughal and post-Mughal administration) tracing British debates about tax assessments through the first three decades of colonial rule in Bengal.