Today, intense business competition and income generation, government regulations, globalization, increasing customer demand and alternative services, have put a lot of pressure on companies, municipalities, etc. In municipalities, it is possible to achieve efficiency in financial and income management and improve organizational performance. The research method is analytical and descriptive and of the correlational type, and in terms of the goal, it is an applied research that tries to investigate and analyze the effect of strategic complexity on the efficiency of financial and income management in marketing and organizational performance. In order to reach the research topic more precisely and also to determine the sample from Cochran's formula, the statistical sample size was selected to 120 people and then Neal and Rose (2018) questionnaire was used in relation to the research topic. Cronbach's alpha was used to measure the validity and reliability of the questionnaire, which confirms the reliability of the research. In order to analyze the obtained data, SPSS and PLS3 statistical software were used in two sections of descriptive and inferential statistics. Based on the research, all the hypotheses are proven, which also shows the effectiveness of the strategic complexity effect on the efficiency of financial and income management in marketing and organizational performance.