I think it is a cleaner solution, but if the 2nd method works better for you then go for it. By cleaner I mean one F1116 for all my foreign income and a 2nd for all by US income deemed as resourced by treaty.
Thanks. I think I that the second F1116 is also cleaner in the sense that the worksheet is not an official form and I dislike having to attach "extra" pages to the return. I'll update on which approach I ultimately use for posterity.
On the inherited IRA my thoughts would be that the inheritance of IRAs would be treated as any other inheritance and not taxable. However, after that the IRA is treated the same as any IRA and distributions are taxed as regular income, gains and losses within an IRA are irrelevant.
Yes this is my opinion too. Particularly as newcomer link: https://www.gov.uk/tax-on-pension-death-benefits
[nonactive] specifically mentions income tax due on inherited pensions in most cases where the deceased is over 75 (they were in my case). There is no detail I can find on foreign inherited pensions but per the treaty, IRA distributions should be considered under these brackets (payments from a drawdown, defined contribution plan). No income tax due on the gross inheritance of due to the deceased having no presence or assets in the UK.
HOWEVER, I'm very interested to hear details from anyone who has successfully used a different strategy - It's a relatively large inheritance, so UK tax on much of the drawdown balance will be at least at the 40% rate (due to the US requirement to empty the IRA in 10 years), so it would be very preferable to only pay US tax rates instead.
Also curious to hear more from Alan or others on "declaring the inheritance". I couldn't find any way to do this as a beneficiary. IHT400 appears to only be for the executor of the estate (and there is no way they are going to do that as an entirely US based person dealing with a US based estate with no UK IHT liability). Topic for a different thread perhaps.