In the United States, if you run a home business, you may file Form 8829 to deduct the cost of a home office in your income taxes. This form has you calculate the percentage of the home used for the home office.
Form 8829 has on line 1:
Area used regularly and exclusively for business, regularly for daycare, or for the storage of inventory or product samples.
And on line 2:
Total area of home
I'm wondering if the total area of the home includes your garage? What about a basement area that has been finished but is not of the quality of the primary living area? I would think line 1 would include such areas since one might use such areas for business purposes, so I imagine the answer should be yes, but since the garage and finished basement areas are sub-par living areas, it seems ingenuine to count them equally square foot for square foot with normal living areas. Should the home use percentage weigh premium living area stronger than sub-par areas such as the garage, and if so, how should this be done?