There are several student performances assessed in Intensive English Programs (IEPs) worldwide in each academic year. These student performances are mostly graded by human raters with a certain degree of error. However, the accuracy of these performance assessments is of utmost importance because they feed data into some high stakes decisions about the students and such performance assessments constitute a large number of students' scores. Therefore, the accuracy of these performance assessments should be given priority by the IEPs. However, the current rater performance monitoring systems which can help the administrators of IEPs to monitor rater performance in performance assessment are away from practicality because they require the use of complex mathematical models and specialized software. A practical and easy to maintain rater performance categorization system is proposed in this paper and it was accompanied by a sample study. Its benefits to the administrators of IEPs and their raters are also discussed besides its practical considerations.