A method and system for automatically estimating budget items based on past transactions and generating a cash flow forecast for one or more accounts. A budget item is determined for each of a plurality of categories of transactions. A frequency and amount of each budget item is determined as a function of an actual transaction count, a date span of actual transactions, and a sum of actual transaction amounts--all of the transactions occurring in the past. For each budget item, a cash flow transaction is determined as a function of a posting date criterion and a selected forecast period. A running balance of the cash flow transactions is determined and displayed. Through the display, a user is enabled to modify individual cash flow transactions to generate a new cash flow forecast, or generate an alternate cash flow forecast that can be compared to the original cash flow forecast.