Abstract: A computer program product, a computer system, and a computer-implemented method are based on spreadsheet software that provides a plurality of user interface sheets including a summary sheet for calculating and indicating spendable income and total estate value for a plurality of different years in a planned range of years; a data input sheet for receiving participant plan information including a participant name, a start age, a retire age, a death age, a consumer price index rate, and a start year; a tax table sheet for receiving currently applicable tax rate information; and a plurality of categorized sheets for receiving and calculating information from which the spendable income and total estate value are calculated. Each user interface sheet is selectable by a user by entering a single input command, for example by clicking a mouse, for fast navigation.