A detective control is designed to locate problems after they have occurred. Once problems have been detected, management can take steps to mitigate the risk that they will occur again in the future, usually by altering the underlying process. An example of a detective control is a physical inventory count, which can spot instances in which the actual inventory is lower than what is stated in the accounting records. Another example is a bank reconciliation, which can detect unexpected withdrawals from a bank account.
A detective control is considered to be less robust than a preventive control, since a preventive control keeps losses from ever occurring, while a detective control may result in initial losses before corrective changes can be implemented.