The Structure of Public Debt and the Criteria of Its Sustainability

Theoretical background: Sustainable development is a wide and developing economic concept. The sustainability of public finances is one of its basic parts. Sustainable public finances are still perceived rather narrowly in terms of their impact on the financial stability of the state. Such an approach to them narrows their perception and should be extended to other aspects such as influence on social and ecological problems of development. Sustainable public debt is and will continue to be a foundation of sustainable public finances. It should be assessed as sustainable public debt, taking into account both its impact on the sustainability of public finances as well as the possibility of providing public services in the future and the achievement of economic, social, and environmental goals of sustainable development.Purpose of the article: The article aims to assess the impact of the differentiation of legal regulations concerning the debt of the central government and the local government subsector on the level of sustainability of public debt in Poland. The paper will verify the hypothesis that the differentiation of debt regulations between the analyzed public finance subsectors has an impact on the sustainability of public debt. The unification of some regulations could probably increase the level of sustainability of public debt.Research methods: Firstly, the analysis of legal solutions based on the desk-research principle was used in the article. Then, public debt sustainability assessment methods were used to assess the degree of sustainability of the central government subsector debt and the local government subsector debt. The stationarity analysis of time series based on the unit root test was applied. The analysis was performed using the KPSS test. An analysis of correlation and regression between the variables public debt and primary balance was performed.  In the aspects that do not have a developed test method, it was proposed to use evaluation methods such as the European taxonomy and the analysis of quantity and value of green bond issues, the share of investment expenditure, and green tagging of expenditure.Main findings: The conducted analysis shows that the regulations concerning the debt of the central government subsector are much more liberal. That fact has a negative impact on the sustainability of public debt. This applies in particular to the aspect of sustainability of development, where the purpose of spending the raised funds is important. On the other hand, the quantitative analysis shows that both parts of the debt in Poland are not sustainable according to the criteria of the methods. However, the debt of the local government subsector is much closer to sustainability in all three aspects.