The Mississippi Collector of Revenue (MCR) designation is the highest level of certification obtained through successful completion of IAAO Course 400 Assessment Administration or IAAO Course 402 Tax Policy in addition to CR1 and CR 2. After successful completion of either course, candidates must complete a comprehensive exam and have a minimum of 3 years of experience in tax collection. The cost to attend IAAO 400 is $650. The MCR Exam is an additional $50.