in SG people already used to, and taken for granted, investment gain without tax.
4% interest, means 4%
in the us if I'm not wrong, need to register with form W-8, any interest received is taxable, so if rate is 4% the nett received is not purely 4% but minus tax
(edited)
nevermind,
just read the comment from BBC Watcher in page 1, from here we can use the "wrapper" which in turn not necessarily pay the tax. but I suppose it's not free to use such "wrapper" services.
...the FATCA has many individual context, need to dig deeper and study more, really.