Tax return for F1/OPT in NYC for 2012 for Chinese student
I'm under F1/OPT status, has been in the US a little longer than 3 years, and I have been freelancing since graduation with my OPT status in New York City, What form should I file for 2012? Do I need to file both Federal and state taxes? What is the difference? Can I use services like Turbo Tax? And Where can I find the tax treaty that I could use between the US and China?
(Also, I'm marrying to a citizen this February, and applying for a green card afterwards, some people say we should file the taxes together, but should I do that for next year?)