Two-tier ERP (enterprise resource planning) is the practice of running two ERP systems at once -- one larger system at the corporate level, and one smaller system at the plant, division, or subsidiary level.
A company may choose to run two-tier ERP for a variety of reasons. For example, it allows an existing legacy ERP system to remain functional across the organization -- which reduces the costs associated with replacing the system -- while letting individual business units deploy ERP systems that may be better suited to their needs.
A two-tier ERP model may also be adopted by organizations that operate globally and must respond to location-specific business requirements in multiple countries. Two-tier ERP may be deployed through in-house systems or through cloud-based ERP.