I will be moving to a place near Chicago in IL on L1B Visa. My company is an Indian company and they have their offices in US in many states registered in US.
My Salary for example is 90K per annum and bonus 10 K. I am married with two kids below 17 years.
I want to know following.
1.what will be the tax deduction from my salary
2. Will I get any exemption against dependents though my family will not go to US with me.
3. Is there any provision for refund of tax paid? I shall be there for 8-12 months.

Thanks in advance.

If you stay beyond 183 days, OR if your salary is from a U.S. subsidiary of the parent company in India, your income is considered to be U.S.-sourced and thus subject to all U.S. taxes.

Those taxes are:
- federal income tax (top rate of 15% for you)
- Illinois state income tax (at 5%)
- Social Security tax (at 4.2%; may go UP to 6.2% in 2013)
- Medicare tax (at 1.45%)

All of these taxes will be withheld from your salary. You will need to file annual tax returns for the federal and state income taxes to reconcile what is withheld to what tax is actually owed. Since there is a special rule for foreign workers that MANDATES you can claim no more than TWO allowances for withholding purposes, you WILL get a refund from the IRS.

You can file JOINTLY with your wife even if she NEVER sets foot in the United States. She will need to get an Individual Tax Identification Number (ITIN) to file jointly with you, and, if she works in India, she will have to declare the Indian income, though that Indian income can be excluded using Form 2555.

You CANNOT claim your children on the return if they spend NO time in the United States in 2012.