In many countries, especially poor countries, a heavy burden of taxes, fees, bureaucratic hassles, and bribes drives many producers into an informal sector. This paper shows that we can attribute the existence of a large informal sector to the fact that, because productive endowments contain important unobservable components, the state cannot adjust the amounts that it extracts from producers in the formal sector finely according to each producer's endowment. Given this fact, we find that if the endowment of well‐endowed producers is sufficiently large relative to poorly endowed producers, or if their number is relatively large, or if the quality of public services is sufficiently low, then the state extracts a large enough amount from producers in the formal sector that poorly endowed producers choose to work in the informal sector. This result obtains both for a proprietary state, which maximizes its own net revenue, and for a hypothetical benevolent state, which would maximize total net output. But, we also find that there exist combinations of the distribution of endowments and the quality of public services such that the policies of a proprietary state, but not the policies of a hypothetical benevolent state, would cause poorly endowed producers to work in the informal sector.