Comprehensive and Detailed Explanation From SAP S/4HANA Cloud Public Edition, Management Accounting documents:

A remaining variance occurs when the system cannot assign a difference between actual and target costs to any specific variance category1. In SAP S/4HANA Cloud, this often results from timing differences in master data updates2.

One primary cause is when the standard cost price of an input material changes after the standard price for the finished product has already been calculated and released3. Because the finished good's standard remains static until the next costing run, the price difference for the component is not captured in the "input price variance" category but falls into "remaining variance"4. Another common cause is when the overhead calculation rate differs from the rate used during the original standard cost estimate5. If overhead rates on the costing sheet are updated after the production order is created, the resulting cost discrepancy cannot be categorized as a standard usage or price variance, leading to a remaining balance on the order6. While rounding differences exist (Option A), they are typically classified under a specific rounding variance category rather than "remaining"7.