Wow, in short it's ridiculously complicated, especially for individual taxpayers with mutual funds. Naturally, mutual fund reporting does not tell us at what rate the foreign tax was calculated, nor on what amount of foreign income, so basically, doing Form 1116 correctly when accounting only for RIC income is impossible. I put the onus for that mostly on the IRS, to be sure (and to the generations of accounts who have invented ever-new ways to game the tax code, leading to new tax regs, leading to more gaming....etc. etc.)
