The main goal of the research was to determine the importance of the income base in the process of financial stability building in local government units. Quantitative and qualitative analysis were used because the comparison method and the diagnostic survey method were involved. The survey covered 189 small communes (up to 5,000 inhabitants) from the Eastern Poland macroregion. The choice of the Eastern Poland macroregion was intentional and dictated by its poor financial potential. The time range of the research covered data for the years 2019-2021. The main source of data was information obtained from the Ministry of Finance and the Local Data Bank of the Central Statistical Office. The obtained results confirmed that among small communes of the Eastern Poland macroregion, the level of income that forming their income base was varied and changed in the analyzed period. The nature of changes in the income base of communes was not uniformed, as the number of communes with the lowest level of total and own income decreased, while the number of communes with a higher level of the mentioned income categories increased. The stability of the number of communes with the highest values of these incomes was also confirmed. The importance of income in building the financial stability of small communes was proved by the opinions of their authorities. Differences were found between the five voivodeships in the perception of significant factors determining the financial stability of small communes in the opinion of their commune heads.