Wave in deck (WID) phenomenon of a wave hitting on the topside for fixed jacket platforms at shallow water condition has been reported as a notable risk to the workability and reliability of these structures. When hydrocarbon from the seabed is extracted for an extended period of time, there might be a reduction in pressure, which allows subsidence to happen. A platform experiencing subsidence promotes the decrease in air gaps, which eventually allows the waves to attack the bottom decks. The impact of the WID generates additional loads to the structure and therefore increases the values of the moment arms. Higher moment arms trigger instability in terms of overturning, which eventually decreases the reserve strength ratio (RSR) values of the structure. The mechanics of WIDs, however, are still not well understood and have not been fully incorporated into the design codes and standards. Therefore, there is a need to revisit the current design codes and standards for platform design optimization. This paper aims at evaluating the effect of RSR values due to WID on four-legged jacket platforms in Malaysia. Base shear values with regards to calibration and modifications of wave characteristics are obtained by numerical simulations. Correspondingly, pushover analysis was conducted to retrieve the RSR. The effects of the contributing factors, namely wave height, wave period, and water depth with regards to the RSR and base shear values, are expected to be analyzed and thoroughly discussed. The work illustrated in this paper is important in optimizing the design life of the existing and aging offshore structures. Outcomes of this research are expected to provide an additional evaluation of the WID mechanics and in return, contribute to the current mitigation strategies in managing the issue. © 2020 IOP Publishing Ltd. All rights reserved.