As far as I can find, as long as the THC content is below 0.03% then there are no special business or tax rules. This lines up with the answer @fubo gave. As far as the Feds are concerned, banks are clear to work with industrial hemp growers and resellers (relevant NY Times article).
Whether banks are open to working with industrial hemp customers is a separate issue. It seems like most are waiting for the SAFER Banking Act to get some traction in Congress. That bill should explicitly confirm what is legal at the federal level in terms of banking, loads, and insurance for both industrial hemp and the rest of the cannabis industry.