If I join a prop trading firm, how will I be taxed in the U.S.? Would profits be taxed as regular income from a job, or would I need to do mark to market accounting? I'm looking into prop trading and would appreciate any info. Thanks.
You need to ask the compliance officer of the firm. Several prop firms issue a K1 statement at the end of the year. It is really simple to do K1 taxes. So with a K1; your end of the year net income is taxed as ordinary income.