This paper aims at carrying out an analysis of a flat slab with drop panels to determine the extent of the SSI effect taking into consideration various types of soil. The analysis is performed in accordance with the finite element method (FEM) with the assistance of ANSYS. For modeling of soil, Winkler model is used where the soil is idealized as a number of linear elastic springs. The study considers five discrete types of soils for analysis. The soil properties are determined according to the modulus of subgrade reaction of each of the soils present at the construction site. While the flat slab with the drop panels is modeled by shell elements, the soil is modeled with linear elastic springs. A comparison of the analysis results illustrates that the soil type plays a crucial role in determining SSI impact on the flat slab system. It is important to note that the type of soil has an effect of the total deformations in the slab where these values are higher for the softer soils. The drop panels also help to minimize the slab deflections and to alter the bending moments especially when operating on softer soils. From the results of this study, it is clear that there is a potential for the SSI effect to influence flat slab design most notably when different soil conditions are considered. Hence, the incorporation of ANSYS software coupled with Winkler’s model is helpful approach in determining the SSI impact on flat slabs with drop panels.