The setback is a frequent type of irregularity expected in complex-shaped buildings. The main purpose of the present paper is to emphasize the influence of setback location on the performance of reinforced concrete building structures under seismic excitation. In this research study, 68 building models with setback values vary from 0.1L to 0.5L, located at various levels, are studied. Non-linear static (pushover) analyses were conducted. All building models are analyzed using a finite element calculation code. The outcomes show that setback irregularity location has a significant effect on the seismic behavior of the structure. Based on the regression analysis of the results obtained in the current study, a mathematical formula is proposed to quantify the effect of setback location on the performance of building structures. The results of this study would aid all professionals in the building sector to anticipate the response of these types of structures during the design phase.