You can use a separate Schedule C to report your day-trading expenses.
From @bwa - Create a separate schedule C (business) where you would report no income, but would deduct margin interest and any other direct costs you may occur. Unlike an investor, these would be business expenses, not itemized deductions.
@bwa 's response is included in the following post, about halfway down the thread: I am a day trader. How, exactly, do I report my investment income ($50,000 in losses, actually) into...
