This paper develops a dynamic model to analyze how government tax policies influence the size of the informal sector in an economy. The model shows that the informal sector naturally declines as an economy grows and transitions towards steady state. Simulation results find that reducing tax rates is the best policy for decreasing the size of the informal sector while also increasing overall output and standards of living. Increasing enforcement alone has a minimal effect, but raising penalties along with enforcement can also reduce informal sector size. The existence of an informal sector slightly reduces steady state capital and output, but actually increases steady state utility levels by allowing for higher consumption.