본 논문에서는 보통교부세 산정에 있어서 기준세율제도와 수입인센티브제도가 지방자치단체의 세수노력과 자치단체간 재정형평화에 미치는 영향을 분석함으로써 양 제도의 역할 분담에 대한 함의를 제공한다. 지방자치단체의 최적화 모형을 이용한 이론적 분석과 그에 근거한 실증분석의 결과는 다음과 같다. 첫째, 모든 자치단체에 대하여 일률적으로 적용되는 기준세율제도는 차별화된 세수노력을 유인하는 데 있어서 유효한 장치라고 볼 수 없으므로 기준세율은 1에 가까운 값으로 인상하여 보통교부세의 재정형평화 효과를 제고해야 한다. 둘째, 기준세율의 인상과 함께 수입인센티브제도가 명시적인 세수노력 유인 수단이 될 수 있도록 인센티브제도를 개편하는 한편 인센티브를 비대칭적으로 적용함으로써 인센티브의 강화에 따른 재정형평화의 저해라는 부작용을 최소화시켜야 한다.
A distinguishing feature of current reform in Korean local share tax system is that of strengthening incentive provision for local tax efforts to deal with the moral hazard problem inherent in the allocation rule of the ordinary share tax. In addition to the inclusion ratio of 80 percent which is one known to be taking the role of encouraging local tax effort, the explicit incentive provision based on the evaluation of local tax efforts is applied more extensively since the late 1990s. This tendency toward tax effort encouragement is not without cost because it inevitably results in a harmful effect on the fiscal equalization role of the local share tax. This paper discusses the effects of the inclusion ratio and the incentive provision on the tax efforts of local autonomous units as well as on the fiscal equalization in Korean local share tax system. Using the revenue maximization model of local autonomous units, the following results are found: there is little evidence that current inclusion of 80 percent applying uniformly to all local autonomous units works as an effective method of inducing differentiated tax efforts, and thus it is desirable to raise the inclusion ratio in order to enhance fiscal equalization effect of the system instead of using the device as an incentive system; incentive provision on local tax effort is required to be redesigned so as to work as an explicit instrument for encouraging local tax efforts; at the same time, incentive provision is recommended to be applied asymmetrically to the units whose tax efforts are higher than a standard level to minimize the negative effect on fiscal equalization of strengthening incentive provision.