HI--I have multiple "identities" with regard to tax:
1. I'm an F-1 visa holder
2. I'm on OPT from Sept.2007-Aug.2008
3. I have benefits of tax treaty, under which I can be exempted from federal taxes up to $5000 a year for wages, and unlimited amount for fellowship
4. I'm a resident alien for tax purpose due to the fact I've been in the US for more than 5 years

In year 2007, I received fellowship as well as wages from three different institutions in 3 different states. My wages did exceed $5000. So, how much, how and when should I pay for my federal taxes?

Many thanks!

Normally the F1 visa is exempt from residency for 5 years. After five years, you will file as resident if you meet the SPT of 183 days. As a resident, if you are Single, you get standard deduction of $5,350 and exemption of $3,400.

To tell you if the above is true is your case or not, we need to know when you entered the U.S. of F1 and your citizenship and are you single or married.

Agreed. More informaton is needed.