<p>“based off of” is incorrect.<br>
“based on” is correct.
From
[based</a> around](<a href=“http://public.wsu.edu/~brians/errors/based.html]based”>based around | Common Errors in English Usage and More | Washington State University)
"You can build a structure around a center, but bases go on the bottom of things, so you can’t base something around something else.</p>
<p>Similarly, you can build something off of a starting point, but you can’t base anything off of anything. Something is always based on something else."</p>