The purpose of selling the Docho was to contribute to the fiscal policies of the Sung Dynasty, which had constantly suffered financial difficulties since its formation, and the sales actually served as an important source of revenue together with the state monopoly on salt.
度牒出売の目的は、その成立当初から財政難に困窮し続けた宋朝の財政政策の一翼を担うことであり、実際に塩の専売制などと共に、国家の重要な財源の一つとなったのである。