Hi I'm an Indian student on OPT. My pay is 75,000 per year. I'm single. This is the pay slip for 2 weeks.

Gross pay: 3,125.00

Standard Deductions:
-----------------------------------------
Federal Income: -514.27
Social Security: -131.25
Medicare: -45.31
California State Income: -186.47
California State DI: -31.25
------------------------------------------
Net Pay: 2,216.45

I got to know that as I'm non-resident alien I'm not liable to pay Social security, medicare taxes. So, I'll ask my employer for refund and ask him not to deduct them from my pay from now on.

How much will I lose in taxes? How much of it will I get in returns? According to the Indo- US treaty will I get any tax benefits? I heard I'll be paying less taxes than someone on H1-B visa. Is that true?

You are paying significantly less than an H-1B visa holder in taxes because of your FICA (Social Security and Medicare) tax exemption.

You get to claim the standard deduction of $5,800 due to your Indian student status under Article 21(2) of the U.S.-India Tax Treaty.

Thanks for responding. So, I'll be paying around $1500 in taxes(Federal income, California state income, California state DI)every month. So, it will total to $18000 per year. So, you mean I'll get $5,800 back as standard deductions.
Can I ask my employer to cut lower money from my paycheck so, that I don't have to wait for an year for refund? Also if get my H1-B visa will I be liable to pay FICO taxes and won't be eligible to claim standard deductions of $5,800.

The standard deduction of $5,800 reduces your INCOME by $5,800, not your TAX. You are eligibel for it whether your visa is F-1 or H-1B at the end of 2012.

If you are SINGLE, the most allowances you can claim on the W-4 is ONE (special IRS rules for foreign nationals). If you are MARRIED, the most you can claim is TWO.

I am an OPT student and had an paid internship last year. Do I get back tax money from my federal and state tax deduction? If yes then what percentage of the deducted amount I am going to get back?

Thanks

Depends on HOW MUCH you earned in the internship.