Until and unless you have graduated in any three or four year Bachelors Degree be it full time or distance, you are eligible for appearing in CAT Exam.

Getting into IIM Calcutta depends on your performance in CAT, henceforth if you get a call, your performance in Graduation, Written Aptitude and Ability Test as well as Personal Interview will be considered.

For more information regarding CAT and rules and regulations do follow the link below

https://bschool.careers360.com/exams/cat