Little is known of the value of eighteenth-century rates and taxes as sources for the urban historian. Corfield, in her study of eighteenth-century Norwich, stated in 1976 that ‘the stereotyped nature of eighteenth-century tax assessments precludes use of fiscal data from national sources’ and this is a fair reflection of the then and to some extent the current orthodoxy, despite Rudé's pioneering studies of the 1960s in which he used land tax and poor rate returns to estimate the wealth of the electorate of Hanoverian London and Middlesex. Schwarz, in a study of late-eighteenth-century London, could still comment in 1979 that for eighteenth-century rates and taxes ‘little is known beyond general impressions’. Recently, however, Wright has thrown interesting light on the use of the Easter books and poor rates of early-modern towns and cities, and the 1986 volume on the land tax edited by Turner and Mills, although still largely concerned with the use of rural land tax assessments, includes three chapters on the value of the assessments in urban and industrial history. The writers hope that city rate and national tax returns might play a fuller role as historical sources, but their optimism is tempered with caution because of the returns' intractability and inconsistency. It is hoped here to reinforce both their enthusiasm and their caution, to reveal additional pitfalls and suggest ways to avoid them and in particular to extend the debate to the neglected pre-1780 assessments and to the city of Bristol.