This document provides information for postsecondary institutions to allow them to review and correct errors in the federal student loan program cohort default rate data that the guaranty agencies provide to the U.S. Department of Education prior to the final calculation of official cohort default rates. Data are provided to schools through a new database, the National Student Loan Data System, which contains loan-level information on the Title IV aid programs. The first section of this guide presents consequences to institutions of cohort default rates from less than 20 percent to greater than 40 percent. The second section describes the procedures used to calculate the cohort default rate including instructions on how to use this information to calculate an individual school's fiscal year 1993 cohort default rate. The third section gives directions on challenging the data prior to the calculation of official cohort default rates such as reviewing the back-up data and presenting the guaranty agency with a checklist identifying disputed accounts and providing evidence to support allegations of error. Also provided are the list of loan status codes, names and addresses of the guaranty agencies by state, and a list of whom to contact at the Department of Education regarding default rate issues. (DB)