Don, TriPacks quote comes directly from the IRS website - I read it myself. It seems to state very clearly that a person in the business of trading his or her own account is not liable for SE tax on the earnings. This is an area of concern to me. Why do you say that Tri Pack was wrong? PS I just re-read your post and I see that you are talking about prop traders. Does anyone else have a different take on SE tax and trading profits?