@mickey @itonewbie  If your client has made a Mark-To-Market election, and is a qualified day trader he reports expenses on schedule C, does not pay se tax, but he reports gains and losses on 4797 sales of business property. He must have filed form 3115 and received approval from IRS, and I believe he can't do this the first year. You should do some research and not depend on comments on a forum as if you do it wrong there could be substantial penalties.