In 1960, Economist Ronald Coase published the article entitled „The Problem of Social Costs”, which is still one of the most frequently cited economic texts raising heated discussions. He wrote that the problem of external costs is twofold, i.e. concerning external effects generated by one entity causing loss for another, where the suppression of injustice is automatically a loss for the first one. He argued that in the case of well-defined property rights and low transaction costs, the problem of external effects can be solved through transactions between parties affected by these effects. Such an understanding of the issue was in opposition to the former attempts to solve this problem through governmental regulation or taxation proposed by Arthur Pigou. In fact, looking through the prism of the system of supporting employment of people with disabilities, the solution causes a dilemma whether it is profitable to limit the employment of efficient people or financial resources of employers in order to provide work for less-efficient people with disabilities, or to leave these people without support on the labour market. In each case, it is about doing the least possible social damage. This article presents both concepts on the example of the system of supporting the employment of people with disabilities in Poland.