With advent of reinforced concrete cement (RCC) as a construction material, retaining walls have undergone a drastic change in their retaining geometry (becoming significantly sleek) compared to the massive rigid gravity walls used earlier, to retain soils. Despite this significant change in their characteristics, the state of the art to compute the dynamic pressure on the wall under earthquake force is to adapt Mononobe and Okabe’s method (M-O method) assuming the wall to be infinitely stiff. The wall is assumed to be fixed at base, behaving as a cantilever beam subjected to a ground acceleration having zero time period, where the effect of foundation compliance is ignored. A counterfort retaining wall (usually deployed, when height of soil retained is > 6 m) is essentially a flat plate stiffened at its edge by the two vertical walls. It thus usually behaves as a two way slab having three sides fixed and one side free, whose behavior is completely different then a cantilever retaining wall spanning only vertically. Thus derivation of seismic response based on M-O method is neither realistic nor rational in this case. Present paper develops a design procedure under earthquake force, where the counterfort retaining wall is considered as a two way slab, and assuming shape functions that satisfy its boundary conditions, the stiffness and mass matrix are developed based on Galerkin’s weighted residual technique. Finally, foundation compliance is considered, assuming the soil as boundary springs in both lateral and rotational mode (as recommended by Wolf) and a comprehensive formulation based on Dynamic Soil Structure Interaction (DSSI) is presented adopting the modal response technique. Results show a considerable difference in outcome when compared to conventional M-O method and indicates that the design procedure as presently proposed in IS-1893(2016) needs serious re-evaluation.