Marijuana is legal in certain states. So if you own a marijuana dispensary it is a logical assumption you can deduct your operating costs? Currently, the answer is no. The Internal Revenue Code (Section 280E) essentially says no deduction for operating costs can be deducted in any business that traffics controlled substances. Since marijuana is illegal federally, you can only deduct cost of sales, but NOT operating expenses. There are several court cases pending on this matter. Stay tuned.