Design and reassessment of pile supported offshore platforms requires realistic determination of the soil-structure interaction. For dynamic and push-over analysis, the lateral capacity of the soil is typically the most critical interaction. With new development in laterally loaded pile design methods, reassessment of platform Inplace, dynamic and pushover analyses were performed using conventional Matlock P-Y method in comparison to the NGI-PETRONAS (2014) and Jeanjean et. al. (2017) P-Y methods for offshore Malaysian soils. A selection criterion was established to ascertain which platforms were to be studied using the various P-Y methods. These methods resulted in different structural behaviour to the modelled platform structure performance which has online monitoring data used to measure actual natural periods. This paper summarises the different results of the dynamic response of the platform due to the various P-Y methods in relation to the different types of selection criteria of soil types, water depth and platform configuration. The newer NGI-P and Jeanjean methods contribute to improved global performance in pushover analyses. These P-Y methods used for reassessment of existing structures provide justification for more effective underwater inspection program.