Public services is a form of service provided by the bureaucracy or government to the public with the following problems : how does the implementation of Samsat Medan Selatan public service principles in increasing tax collection of motor vehicle tax, this research uses a descriptive qualitative method that uses data collection techniques, observation, interview, and documentation. Quite good but if seen from the realization of the tax revenue of two- wheeled motorbikes there was a decrease from 2016 to 2017 based on the results of the study it can be concluded that the Samsat southern field public service principle in increasing tax collection oftwo-wheeled motor vehicles is good enough, but what needs to be improved is how to motivate the public to want to participate in pay tax especially two-wheeled motor vehicles.