@GeoffreyG Thank you for that insightful answer. I have a similar situation being an Iowa resident with a CA 541 K-1. I also am the one preparing the 1041 and 541 and K-1s for the trust. (My California siblings are the other beneficiaries.)
The trust income is made up of interest (line 1) on the 541 K-1 and "other portfolio and nonbusiness income" (line 5). I read the instructions for the 541 and K-1 and I think this is intangible income and would not be California source income for non-residents. Do you agree? TurboTax Business did not seem to ask me any questions about CA source income but there is nothing in Column (e) for lines 1-14 in the 541 K-1's that I prepared using TurboTax Business.
If it's not CA source income then I think I will not have to file a CA 540 based on the thresholds you mentioned, which would make me quite happy. Looking forward to your answer. Thank you.
