Choose your own adventure. This is what we get paid the big bucks for.

Depending on materiality:

- Elect not to file the 1116, because then you don't care

- Assume all are foreign

- Look at the dividend detail and pick out all the items that have foreign taxes withheld and assume those are 100% foreign

- Look at the dividend detail and pick out all the items that have ADR in the name and assume those are 100% foreign

- Google every mutual fund to determine the percentage of foreign source income, then multiply

- Ask your client to ask their investment advisor, whose hapless assistant surely has nothing better to do and wouldn't consider just blowing you off