Implementations of the present invention provide systems, methods, and apparatus for stopping unauthorized transactions before they are processed, as well as for creating and using one or more sub-accounts. For example, a debit or credit account can be activated or deactivated at will through various spend control mechanisms, which can be limited by specified time periods, numbers of transactions, and/or monetary amounts. Further implementations also relate to using a unique 6-digit identification number (or biometric information) that is known only to the account granting institution and the primary account owner for the various types of activation/deactivation.