A method and apparatus for modifying data synchronization of a portable computing device responsive to a data plan associated with an account associated with the portable computing device are disclosed. If the data plan specifies a data quota identifying a maximum amount of data for communication by the portable computing device, a data synchronization setting determines whether to minimize the frequency of synchronization between the portable computing device and a server or to dynamically modify the frequency of synchronization based on data usage. If data synchronization is dynamically modified, the data synchronization frequency is modified based on an estimated data usage of the portable computing device over a time interval. The data synchronization frequency is modified based on the difference between estimated data usage and the data quota and is reduced if the estimated data usage equals or exceeds the data quota.