I have income reported to me in box 16 of form K-1. The K-1 is from a U.S. investment fund that owns a stock portfolio and box 16 is for foreign transactions. The income in box 16c is dividend income from ownership of foreign stocks. TurboTax is asking me to identify how much of the foreign income in this box is U.S. sourced and how much is foreign. How do I answer this question? The default answer in Turbotax is 100% U.S. sourced.