Structural engineers ensure that buildings can withstand different types of loads and operate safely throughout their lifetime without endangering human life. During project delivery, ensuring safety requires completing critical tasks, such as performing a deflection check for reinforced concrete slabs. ProtaStructure allows you to design RC slabs based on the design and seismic codes you follow with advanced tools and parametric wizards. In addition, it allows you to perform a deflection check and see the impacts of the loads acting on the members you design. This document provides an in-depth overview of the deflection checks conducted by the ProtaStructure according to the Turkish code, TS500 regulations. It includes numerical examples of two-way slabs and cantilever slabs to illustrate the calculations and parameters considered by the software. Moreover, the document explains all the mathematical calculations performed by the software, making it easy to understand.