From my understanding to determine "living space" the area must be above ground level. Which is why raised ranches show up well. However, towns tend to vary on some of issues as to how to record a finished lower level. I did have the town add a bedroom and bath (in my basement) to the number of rooms but it did not change living sq. ft. Basements are included in total square footage. If you want to see how your house shows up on town records go to http://visionappraisal.com/ and go to your town and put in your street address. It will show total sq. ft and living space..
If I can be of any further help, feel free to contact me.