The rules for paying taxes on international investments can be either easy or complicated, depending on how you've invested.
If you've incurred capital gains or income from any direct investments in another country, you'll owe tax on them at the same rates as your U.S. investments.
Mutual funds that invest in other countries often pay taxes on interest and dividends in those countries. If a fund meets certain requirements, it can allocate your share of the foreign tax it paid to you, which you can claim as either an itemized deduction or a foreign tax credit on your income tax return. You'll see the amount you can claim on the Form 1099-DIV that the fund sends you.
If you're invested through a mutual fund or other entity based outside the U.S., the situation is a little more complicated. Since these funds can't be sold in the U.S. unless they meet all of the regulatory requirements imposed on domestic funds, they don't generally provide the same tax reporting documentation. But if you're invested in one, the IRS requires you to calculate your share of the income and your tax on it. To get it right, you'll probably want to consult with your tax adviser.
Complicated taxation is one reason most experts advise that you do your international investing through U.S.-based funds, ADRs,
and international investments sold on U.S. exchanges.
Jeffrey Rosensweig, Goizueta Business School, Emory University
Mutual funds that invest in other countries often pay taxes on interest and dividends in those countries. If a fund meets certain requirements, it can allocate your share of the foreign tax it paid to you, which you can claim as either an itemized deduction or a foreign tax credit on your income tax return. You'll see the amount you can claim on the Form 1099-DIV that the fund sends you. 
Jeffrey Rosensweig, Goizueta Business School, Emory University 