Some areas do and some don't. We don't have basements here where I live but when I was in Virginia we did and they were added in the sq footage if finished and heated. An appraiser will add the space but give it a lower value per sq foot than finished space above ground.
I just asked my agent this earlier this week - if listed correctly no. So if you see a home you like but is a little on the smaller end don't forget about the basement opportunities! It has opened a whole new market for me and my husband.
Finished basements do not cound in square footage. The criteria fo rit to meet to be counted pretty much outlines the space not be a basement but be above ground. It does add to value, just not square footage