Public aid for SME’s evokes many controversy. Politicians generally support this idea. In practice, it is difficult to support all companies, even just the micro and small. Anyway subjective approach of supporting "per se" a particular group of companies is rather irrational and inefficient, even if they are e.g. technological companies. Support should rather reward certain behaviors of enterprises (incentive approach) or reward enterprises in a specific situation which puts the company unfairly disadvantaged (situational approach). Analyzing fiscal preferences in Poland, it is clear that they basically refer to three areas: grant exemptions from income taxes, the possibility of past losses deduction and the exemptions in Special Economic Zones. Other preferential solutions, known around the world do not exist in the Polish tax system or the scale of their use is marginal. So other preferential tax solutions for small and medium-sized enterprises should be introduced or not? This question is difficult to answer. According to researches carried out by Lewiatan Council Tax most of the interviewed people are in favor of the lack of tax benefits for the SME sector. Undoubtedly, the introduction of new incentives require reliable calculation of costs and benefits.