Tandem-based solar cells reflect a significant advancement in photovoltaic (PV) technology, offering the potential for enhanced power conversion efficiency (PCE) compared to the widely used but limited single-junction cells. This chapter provides an overview of computational studies on tandem perovskite solar cells, focusing on their principles, structures, and benefits, and highlighting their potential for high-efficiency solar energy conversion. It explores the working mechanisms and structural advantages of tandem configurations, which improve light absorption and reduce energy losses. The chapter also covers the theoretical foundations of both perovskite-on-perovskite and heterojunction perovskite tandem architectures, emphasizing the critical role of interface engineering in enhancing device stability and reducing degradation. Experimental evidence is presented to support the feasibility of tandem perovskite solar cells, demonstrating recent advancements in performance. Additionally, the limitations of computational models, such as accuracy and resource constraints, are discussed, underscoring the need for a combined approach of computational and experimental research to overcome challenges and drive future advancements in high-efficiency, stable tandem perovskite solar cells.