In order for any part of a home to be considered in the square footage calculations, i.e., part of the living space, it has to meet certain basic criteria.
First, it has to be heated, since in most parts of the country you cannot live in it all year round without heat.
Second, electrical, fire, and other safety codes must be met. You need so many outlets per foot of wall space, a smoke detector, and usually 2 emergency exits from the area, Usually this is accomplished with a door and window. Since you don’t have any windows…I’m not sure. I'm also not sure about ceiling height
Third, exposure to hazardous materials, such as insulation and such, cannot be. Essentially, you need to cover those problems with drywall or equivalent.
Last, it is your municipality that determines what is and is not living space. If you want to finish your basement and count it as living space, you will need to get approval from them. When you are done with the project, they will issue you an occupancy permit, officially designating it as living space. Of course, you run the risk of raising your taxes, but on the other hand, you cannot legally count the space as part of the house’s living space, for loans, resale, or whatever, unless it also appears on your assessment report. It’s one of those nasty ways people who finish their basement without a permit get burned when they go to sell.
I think those are the main points. Your municipality may have more detailed requirements you will need to follow.