Square footage listing vs appraiser

[Alexander Chavez]

In Chicago, is there a certain height a finished basement needs to be in order for it to count as square footage. Is it different for an appraiser than when listing on the MLS?

I am asking because I know of plenty of houses that do not have tall basements(less than 7 feet), but when they are listed to be sold, the agent has included the finished basement as square footage, which should potentially help increase the price of the home.

I have a potential property that has a basement that is about 6'9" that I plan to finish and put a bedroom in as well. When it comes time to sell what limits me from including it as part of the square footage so that it is considered in the ARV?

Also when running comps on similar sold properties, how does one know that the square footage is accurate on the listing?