Three studies concerning software reengineering conducted by the US Internal Revenue Service (IRS) in 1991 and 1992 are described. The situation at the IRS-aging, piecemeal information technology systems maintained by a large staff-is familiar to many institutions. Tax records are processed across multiple locations, platforms, computer languages and data file structures. The three software reengineering studies looked at methods, CASE tool support, and a prototype project using reengineering methods and tools. Critical issues were discovered that were broader than the mechanical definitions of methods and tool technology, namely: planning an orderly transition, organizational readiness, and business reengineering. These point to the organizational and technical frameworks which support business practices of software engineering.