Depends on what you're using as hardware.
If you have a mining machine that is solely used for mining and absolutely nothing else, then you can easily deduct the depreciation of the machine and the electricity the machine uses (a reasonable recalculation should work for cost of electricity). However, if you have a personal computer that you sometimes use to mine, and sometimes use to go online / watch movies / etc., you're not going to be able to deduct anything for this.
The IRS has been making a big push recently targeting business items that have personal use, which is why I'd advise against anyone trying to deduct the cost of their main computer as a bitcoin expense.
Thanks this helps. MOST hardware is mining-specific, but I do have some hardware I will have to think about. Do you know if there is any kind of % test of time that can be applied to determine if it's deductible, or even partially so, or is it basically that ANY personal use would exclude it? My kids logging in for a few minutes to check on homework a couple times a week on a machine that continues to mine basically 100% of the time is one example.
Not trying to split hairs, so hopefully it doesn't come across that way. I appreciate your feedback.