I am currently on OPT(starting Jan,08). I am working in California.

I have filled 3 exempts in W4 form.

What would be the exact percentage of tax that will be deducted from my salary?

It would depend on HOW MUCH you make, plus whether you filed SINGLE or MARRIED.

I am currently on OPT(starting Jan,08). I am working in California.
I have filled 3 exempts in W4 form.
What would be the exact percentage of tax that will be deducted from my salary?

Normally on OPT you can fill more than 1 allowance on your W4 since you will file nonresident return and can claim only your own exemption and itemized deductions. Your income may be exempt from FICA taxes.

For you there may be some more deductions as per tax treaty. So we need more info:
Your visa status and when did you enter the U.S. and are you married and your citizenship?

Thanks for prompt reply.

I came to US in July, 06 on F-1 visa for MS. Completed it in Dec, 07. And now I am on OPT starting Jan, 08. I am working in California and earning 62.5 K annually. I filled W-4 form with 3 exempts.

I am single and have citizenship of India. My H1-B will be files in April, 08.

So, please tell me how much percentage of my income will be with held as tax till the time I am on OPT? OR What percentage of my income will I get after the tax.
Please let me know if you want to ask more questions.

Your tax liability will be somewhere in the $10,000 range, about 18%.

For California, you will owe about $3,200, about 5%.

Great!
Thank you so much.

Glad to help!