Reinforced concrete (RC) flat slab not only provides benefits in terms of floor-to-floor height, aesthetics but also facilitates the installation of formwork, reducing construction time for the project. However, this type of floor structure is prone to punching failure at the slab-column connection, which can lead to the collapse of the structure. Corrosion of the steel reinforcement at the connection of the slab-column makes the behavior more complex. Predicting the load-bearing capacity in this zone needs to account for the factors caused by corrosion. This paper presents the results of evaluating the punching shear strength of corroded RC flat slabs through 123 experimental databases from previous publication based on three building codes: ACI 318-19, Eurocode 2, and TCVN 5574:2018. The statistical metrics indicate that TCVN 5574:2018 provides the safest prediction results. Additionally, a formula derived from nonlinear regression analysis is proposed to enhance the accuracy in predicting the punching shear strength of the corroded RC flat slabs.