An IT-OT dependency is the operational link between business IT systems and operational technology, such as manufacturing, process control, or other production environments. In practice, it means an action in one domain can affect the other: identity services, laptops, engineering workstations, patch servers, remote access tools, or file shares in IT may be needed for OT to function.
This matters because attackers often target the IT side first, then use trusted connections to reach sensitive operational assets. A compromise of a developer workstation, administrator account, or internal service can disrupt production, shut down equipment, or block monitoring and safety functions. Defenders reduce this risk by segmenting networks, limiting trust paths, using strong access controls, and testing how failures in IT would affect OT. The goal is to keep a local IT incident from becoming a business or production outage.