a system and method for verifying charges on a customer bill includes a computers for downloading , from a mainframe computer , to a local server billing data associated with a customer account , populating a database with a portion of the billing data , performing pre - calculation functions on another portion of the billing data and populating the database with results of the pre - calculation functions , displaying predetermined categories of information stored in the database , calculating the taxes for each of several charges in the billing data and storing tax results in the database , and comparing the tax results with tax information on the customer bill .