I plan to start working in the USA on July of this year under a H-1B Visa. I was told that my taxation of income will depend on whether I am categorized as a non-resident alien or as a resident alien. I prefer to be taxed as a non-resident as I have a stock & bonds account in Mexico that I would not like to pay taxes in the USA. There is no capital gains tax in Mexico (unbelievable, I know). I have been reading that in order for me to qualify as a non-resident I need to do the "Substancial Presence Test", but I do not understand something... During my first year of my H-B1 stay in the USA I HAVE to be a non-resident, right?. So at least during the first year I will be qualifying as a non-resident?

Thank you in advance.

Even if you are a nonresident, the income earned while present in US is taxable in US.
If you are single and did not complete SPT in 2010, you will file nonresident tax return. Your U.S. Tax Return: The U.S. Visas (http://taxipay.blogspot.com/2008/08/us-visas.html)