In this paper, we identify factors that impact software maintenance effort by exploring expert software maintenance estimators’ knowledge about corrective maintenance projects. We use a qualitative approach to identify the issues important to these experts to derive their effort estimates. We find seventeen factors (rated and rank ordered by importance) that affect corrective maintenance effort and include constructs related to developers, code, defects, and environment. Several of these factors that have a comparably strong influence on corrective maintenance estimation are unique to corrective maintenance and are not generally observed in established software estimation models. The results enhance organizations’ ability to effectively manage maintenance environments by focusing attention on the identified areas. For future research, these results represent an important step toward developing a comprehensive and accurate corrective maintenance effort estimation model
