According to the IRS, $23 billion in unpaid individual income tax debt existed in 2001, its most recent estimate. The notice phase is the first of IRS's three-phase process to collect unpaid debt. IRS annually sends notices to millions of individual taxpayers about billions of dollars of unpaid tax debt. Congress and others have questioned IRS's collection process's effectiveness. This report discusses: (1) how well IRS has established objectives, performance measures, and responsibility for reviewing notice-phase performance; and (2) how well IRS's business rules for sending notices to individuals help assure that the collection notice phase is achieving desired results at the lowest costs. Includes recommendations. Charts and tables.