The paper presents the qualification of heat and electricity produced in plants using waste as a fuel. It also concerns the issues related with the possibilities of participation in the system of emissions trading. The basis for such considerations is the content of biodegradable fraction in waste, which is treated as “biomass”, based on the definitions set out in relevant legislation. It is necessary to determine content of biodegradable fraction in waste in order to establish the purposes. Two ways of settling share of energy from renewable energy sources were introduced. The first, was based on direct measurement of the share of biodegradable fraction in the tested waste. On the other hand, the second is involved with certain types of waste. Thus, the share of biodegradable fraction is determined by flat-rate value. An applicable auction system does not guarantee the financial support for electricity produced from renewable energy sources, even if it is classified so. A company selling heat to end users is obliged to purchase the heat from renewable energy sources, including thermal treatment plants using municipal waste. The maximum level that the company is obliged to purchase is equal to the customers’ demand. Both the municipal waste incineration and hazardous waste incineration plants are exempted from the obligations provided in the Act on system of emission trading. This applies only to the waste incineration plants, which incinerate only the municipal waste or hazardous waste and the plants which are processing waste, not producing of heat. When an installation uses alternative fuel, it is not automatically excluded from participation in the system of emission trading. For biodegradable fraction of alternative fuel, the emission factor equal to 0 can be used. For the remaining alternative fuels, an emission factor determined on the basis of laboratory tests must be assigned. In order to demonstrate that an alternative fuel contains biomass, it should be analysed through laboratory testing. The energy recovery from the waste containing biodegradable fractions should be carried out maintaining formal and legal requirements for waste incineration.