Regulatory cycles: Or why does the tax code get bigger every year?

Modern democracies use regulatory structures to control many types of behaviour. In the theoretical literature these regulatory structures, which could be income tax codes, sets of tariffs or traffic laws, are presented as systems of rules that are constant over time. However in practice regulatory structures are often observed to change over time. A model is developed to explain why we might observe regulatory structures cycling between periods of increasing complexity and episodes of reform. The model is used to identify the features of stable versus cyclical regulatory structures.