i need to explain and not too long answer i need short answer .

ELS, an S corporation, reported a business loss of $1,000,000. Ethan, ELSs sole shareholder, is involved in ELSs daily business activities and he reports $1,200,000 of taxable income from sources other than ELS. What must you know in order to determine how much, if any, of the $1,000,000 loss Ethan may deduct in the current year? Explain