US / UK estate tax rules

Hi all,

My mom is getting older and has asked me to help her start getting her affairs in order to make things easier for me and my siblings when she passes on (my father has already passed). Estate planning is a bit of a mess: she is a UK citizen who lived in the US for many years. My siblings and I are US/UK citizens who live in the US. My mom owns a house in the US (that my brother lives in, in Minnesota) and shares ownership of a house in the UK.

As I understand it, the inheritance rules in the UK are relatively straightforward: there is a 325,000 GBP threshhold, above which the total value of the global estate is taxed at 40%.

In the US, it is not so clear. From what I have gathered, any inheritance of UK assets will not be taxed in the US, but US property may. I have been reading up on the 'pro rata unified credit' which is intended to help avoid double taxation, but it is not clear to me if that applied to all US property (i.e. including real estate) or just bank accounts and US stocks. Without the credit, the exemption in the US for inheritance from a non-citizen, non-resident is just $60,000.

Concretely, I have 3 questions:

1) Does the pro rata credit extend to US property? If so, my understanding would be that we would then be exempt from US taxes (total value of US assets at the moment is well below $1 million).

2) My brother has been debating buying the house. From my research, it seems like it would be preferable that he pay full market value, to avoid triggering any gift tax. The house is not in great shape, and I suspect it is worth less than the value at which it is currently assessed. Should my brother just get a professional assessment and pay whatever value they suggest, or can my mom offer a discount, to offset the fact that we would be saving money by avoiding a typical house sale process. How much latitude is there in the full market value?

3) If I am understanding the tax rules correctly, cash held in a US bank would be subject to US estate tax, but if it were transferred to a UK bank it would not. Is it really so simple?

Without getting into complicated tax avoidance strategies, it seems like the best course would be for my brother to pay full market value for the house, for my mom to transfer all cash to the UK, and then we would be left only paying UK estate tax on her assets. Does that seem reasonable, or is there something I'm not considering?

I know I'd be better off going to a tax professional, but we have not had luck finding someone with expertise in US and UK law, and we have been advised that it will be hard to find someone to take an interest given the relatively low total value of the estate (about $1 million combined in US and UK assets).

Many thanks in advance for any tips or places to look for more info.