As someone who more and more feels that I would clearly be considered a "trader" in the IRS view based on all the things they say to consider (my tax return is like an inch thick!), I'd like to first share a website article I read this week:
http://www.marketwatch.com/story/tax-strategies-for-day-traders-2015-02-25?link=MW_latest_news
The article makes it seem rather simple. According to the article, the trader simply adds a Schedule C to the return with a letter of explanation, and on the Schedule C will go the business expenses and margin interest. The advantage is in the treatment of the expenses on the Schedule C, and the treatment bypasses the usual limit of 2% of AGI while reducing AGI.
The article also states the added benefits of becoming a "mark-to-market" trader, which eliminates wash sale rules, as well as the $3000 limit for capital gains losses. It appears Part II of Form 4797 is the form to utilize for gains and losses for "mark-to-market" trading.
So if the trader has little business expense, no margin interest, no wash sales, and net profits on the year, there is really no benefit to TTS. But if any of those 4 apply, it seems it really should be a consideration to treat the trading like the business it really is. In my case...it's been a good while since I've had net losses, I have little in business expense (although could probably consider home office), I have just a few wash sales, but I have quite a bit of margin interest each year.
Some may have very good reasons to form an entity, but I would think that most full-time traders need not consider doing so.
Thoughts?