The main objective of this study was to evaluate the effect of decentralized tax policies on district development in Rwanda. The research was guided by the following specific objectives: to examine the effect of rental income tax policies on development of Rwamagana district, assess the effect of immovable property tax policies on development of Rwamagana district and identify the effect of trading license tax policies on development of Rwamagana district. This study used descriptive and analytical, whereas descriptive research also called statistical research the main goal of this type of research was to describe data and characteristics of what was being studied. Quantitative and qualitative data used to effect of decentralized tax policies on the development of district. The population of this study was 246 including tax collectors, District administration and Finance officers, Sector administration and Finance officers, Accountants, Ngali holdings staff and staff at cell level. Using Slovin's formula, researcher estimate how big of a sample they needed to get reliable findings. Each stratum has its own simple random sample selected 152 respondents from it, in a size that is proportionate to its result of the increasing number. The researcher gained the information from the primary data obtained through a questionnaire, interview and document review applied as to obtain secondary data. Descriptive statistics were used to obtain the frequencies and percentages, in addition inferential statistics, mainly the correlation model, Analysis of Variance to test the relationship among the variables (independent). The study used SPSS (Version 21) and Microsoft Excel to analyze the data. The model includes predictors such as Trading license tax policies, Immovable property policies, Rental income tax policies. The R value of 0.876 indicates a strong relationship between the predictors and the Development of Rwamagana District. The R Square value of 0.767 indicates that approximately 76.7% of the variability in the outcome variable can be explained by the predictors in the model. Overall, this model summary indicates a significant effect of the decentralized tax policies on the outcome variable Development of Rwamagana District Specifically, Rental income tax policies have a coefficient of (β= 0.473, t=7.499, p