Final answer:
A Relief for Cause NCOER is mandatory when an NCO is relieved from their duties due to substandard performance or misconduct, as required by military regulations.
Step-by-step explanation:
The question 'Para 3-55 When is a Relief for Cause NCOER mandatory?' pertains to U.S. Army regulations regarding the Noncommissioned Officer Evaluation Report (NCOER). A Relief for Cause NCOER is mandated when an NCO (Non-Commissioned Officer) is relieved from their duties for cause. This action is taken due to substandard performance or for misconduct. According to the regulation, an NCOER must be initiated whenever an NCO is relieved from their duty position under adverse conditions or due to inefficiency, as documented by an investigation or by a relief for cause memorandum. The timeline for initiating this report is typically within 30 days of the relief action.