What tax can I expect on US stocks in a UK ISA?
non-resident aliens to the US do not pay capital gains on US products. You pay tax in your home country if you have done a taxable event in your country. http://www.investopedia.com/ask/answers/06/nonusresidenttax.asp#axzz1mQDut9Ru but if you hold dividends, you are subject to US dividend tax. The UK-US treaty should touch on that though.