The Once Only Principle is a data management concept in cybersecurity and digital services. It states that organizations should ask users for a specific piece of information only once. After collecting it, the organization must reuse this information internally whenever needed, rather than requesting it again. This principle reduces user frustration, streamlines processes, and minimizes the risk of errors or data inconsistencies. In addition, it helps protect user privacy by limiting the number of times sensitive data is transmitted or entered, reducing the attack surface for potential breaches. The Once Only Principle is especially important in government and public sector digital services, where citizens often interact with multiple agencies. By adhering to this principle, organizations can improve user experience, increase operational efficiency, and enhance overall data security.