Historically, governments contracted with private agents known as tax farmers to collect taxes. This paper develops a theoretical framework for determining when a welfare-maximizing government should choose tax farmers over bureaucratic tax collectors. While bureaucratic collectors have an incentive to shirk and raise collection costs above least costs, profit-maximizing private collectors tend to reduce tax evasion below the optimal level. Generally, the choice of collection methods depends on a comparison of the welfare loss associated with monitoring in the bureaucratic setting and the welfare loss associated with overdetection of evasion in the private setting.