Background and objective: In recent years, the reform of the administrative system and the improvement of management have been pursued as the main prerequisite for the growth and development of the country, so that the quality and effectiveness of the management of the executive system as a vital and important factor in the realization of the development plans and prosperity and welfare of the nation’s seems necessary. The purpose of this research is to provide a model of transformation in the administrative system of the country's tax affairs organization. This research was carried out in Tehran province and it was an interpretative-inductive survey and it was done with quantitative-qualitative method. The statistical population of the quantitative part includes all the employees of the Tax Administration and the qualitative part includes the experts and managers of the Tax Administration.
Methodology: The tool of the quantitative part was the questionnaire and the qualitative part was the interview. In order to analyze quantitative data, structural equation model (SEM) was used with Lisrel software and MAXQDA software was used for qualitative data.
Findings and conclusion: results in the quantitative part showed that the components of the transformation model in the administrative system have a positive and significant effect on each other and the model has a favorable degree of fit. The results of qualitative part indicated that the transformation components in the administrative system of Tax Affairs Organization include causal, contextual, intervention, strategies and main dimensions, and these components also have sub-components.