UK-USA tax treaty

[marinakit]

A dual UK-USA citizen lives and works in the USA. He has investments in the UK that he opened before he moved to the US which are taxed at source. Also, he has a partial interest in a house. According to the UK law because he is not utilizing his part of the house, his mom, who is another owner and lives in the house, is paying him rent (FRV). He files a UK tax return, but is not paying any taxes due to low amount of rent being wiped out by the personal exemption.
A US CPA advized him that according to the UK-USA tax treaty he does not have to show his rental or investmnent income on his US tax return. (As for rental, he will have a loss due to the depreciation and most likely won't be able to claim it because of high wages or the deduction may be limited.)
Do you agree?

[mwcpa]

without looking at the treaty which may or may not allow for such treatment, under the law, a US citizen/resident is subject to income tax on worldwide income and all income from all sources must be reported.... there are some crazy things in the treaties, but I would think this treatment is not one of them.....

one needs to read the treaty and the technical explanations that come with it.... www.irs.gov/businesses/international/article/0,,id=169552,00.html (link to it)