Hi ,
I am a student who has graduated with a masters degree in California and I have a job in virginia . I am on a F1 status and my optional practical training commences on the 26th of oct 09. I was wanting to know as in how much tax deductions are the students on optinal practical training subjectable for ? I exactly have no idea as in how much of my salary would be going in as taxes .
Thanks for reading this long question.!

You are subject to the same federal and state income taxes that U.S. citizens pay. You will have these taxes withheld from your salary at the SINGLE with ONE or ZERO allowances (IRS regulations prevents you from claiming more than one allowance), so you WILL over-withhold and have to file a tax return to get the excess back in the form of a refund. This is done to ensure that enough taxes are withheld to cover your tax liability. You will file Form 1040NR or 1040NR-EZ plus Form 8843 for each year you are under the OPT program.

While on OPT, however, you are exempt from FICA (Social Security and Medicare) taxes. Make sure your employer is aware of this fact to ensure that he does NO withhold these taxes.

HOW MUCH is withheld for the income taxes depends on your level of income. Realistically, expect the withholding to be about 15% for the IRS and 6% for Virginia.