In this study, general financial characteristics of the cooperative banking sector in Poland in the years 2010–2018 were discussed, presenting the most important balance sheet data and profit and loss statement information. The focus was also on the analysis and assessment of the importance of state government and local self-government institutions (general government institutions) for cooperative and affiliating banks. An attempt was made to establish the relationship between the receivables of state government and local self-government institutions and the liabilities of these institutions, versus debt and capital instruments broken down into cooperative banks, affiliating banks, and the entire sector. As a result of the conducted research, it was found that cooperative banks constitute the core of the cooperative banking sector, and that they achieve a better and more stable net financial result; moreover, they systematically increase their balance sheet total – even faster than commercial banks – as well as increasing the size and quality of receivables and maintaining good level of liabilities. Central and local government institutions, although they do not show a large share in the discussed financial figures in the cooperative banking sector, nevertheless play an important role primarily in cooperative banks, but also in affiliating banks.