Not every generic product requires an in vivo bioequivalence study. The requirement depends on the drug substance, dosage form, route of administration, drug properties, and applicable regulatory guidelines. During the generic drug development process, developers first evaluate whether an in vivo study is necessary or whether the product may qualify for a biowaiver based on factors such as solubility, dissolution, and other established criteria. For some immediate-release solid oral dosage forms, a suitable biowaiver pathway may be available, while other products may require a clinical bioequivalence study to demonstrate comparable performance to the reference product. Therefore, the approach can vary for each generic product development project. Understanding these requirements early can help plan the development of generic drugs, manage the generic drug development timeline, and select the appropriate testing and regulatory strategy.