Are non-US citizens trading on US stocks/options subject to tax?

If you are trading from outside the US you should pay taxes on any profits in the country you are trading from. You should check with the tax department in the country you are trading from.

You, lucky sir, if you are in fact a non-resident alien (in the US less than half of one year), are tax-free for capital gains with a few caveats and such.

Generally speaking, if you are a long term investor in non-real estate securities and spend no time in the US, your capital gains are not taxable.

If the short term gains appear to be from trading and not investing, they may be taxable.

Dividends are taxed at a merciless 30% with exceptions, unless there's a tax treaty between your home country and the US to say otherwise.

That said, you're still required to pay the capital gains/income taxes on all your income, home and abroad, in your home country.

Any tax experts feel free to edit for accuracy.

A quick update for people finding this thread through Google. With the help of a few awesome Bogleheads, I compiled all the relevant research done into two Wiki articles:

• Nonresident alien taxation
• Nonresident alien with no US tax treaty & Irish ETFs

This includes comparing US to Irish domiciled ETFs, how to calculate tax withholding leakage and estate tax concerns.

Hope you find this useful.