The Executive Order 14137 establishes a new order of succession for the Department of the Treasury if both the Secretary and Deputy Secretary are unable to perform their duties. The succession list starts with any Under Secretary and proceeds through several key officials, including the General Counsel and Chief of Staff, among others. The order specifies that individuals in acting positions cannot serve as Secretary, and the President has the discretion to deviate from this order. This Executive Order also revokes a previous order from August 2016 related to Treasury succession.
Simple Explanation
If the top leaders at the Treasury Department can't do their jobs, this new rule sets a list of who should step in. But the President can choose differently if needed.