Anyone over 6 figures actually filing as a Pro?

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The IRS always uses "facts and circumstances" to determine if a person should file as a professional. You will never find any specifics or criteria that will push a person over the ledge to qualify as a professional. The example of making $100k as a sole source of income is probably going to fall into the professional category.

The IRS is very aggressive with regard to anything reported as other income on a tax return. I can't think of any situation where the IRS would not try to collect SE tax on $100k of net gambling winnings, except in a jackpot situation. I would also add that multiple years of net gambling income would also hurt the case to keep the income as non-professional.