hi,

see migration certificate is issued when a candidate transfer to another institute while pursuing in any regular courses like bachelors course/ diploma course  in any particular institute, but due to some reason want to do pursue the remaining of the course in another institute or want to take admission in  another institute. now see if you dropout after several months of study and irregular in course curriculum you may not get the migration certificate. another thing is many candidates takes gap of year after 12th course. so in some of the institute you may not need to produce the migration certificate if you take fresh admission in first year of any particular course. however in that case of admission you may need to submit the school leaving certificate.

hope you may understand.