This question already has an answer here:

I have bought a Tab A for development, and I was hoping that I would be able to receive the latest update to Marshmallow. Seeing that it is one of the most recent models, it would be a no brainer not to update it. However, the S7 has been released along with the Samsung/Android hybrid of Marshmallow yet lo and behold my Tab remains on 5.1.1. Is there any outlook to update the Tab? If yes when? If no why? If uncertain, would it be possible for me to get a beta release?

marked as duplicate by Izzy May 5 '16 at 23:05

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.