A compensating control, also called an alternative control, is a mechanism that is put in place to satisfy the requirement for a security measure that is deemed too difficult or impractical to implement at the present time.
"Compensating controls are additional security measures that you take to address a vulnerability without remediating the underlying issue." A compensating control is a control that reduces the risk of an existing or potential control weakness2 In this case, the lack of segregation of duties in the accounting department is a control weakness that increases the risk of fraud or error. The quarterly reviews by a different officer are a compensating control that reduces this risk by providing an independent verification of the transactions recorded by the controller.