I am on L1 visa & I am in US with my wife (L2 visa) from October . We both are non-resident alien.
Can I file Joint return with my wife & get the benefit of dependent exempt.
Or
Can I file "Marrid as Separate return" & don't file for my spouse

You have two choices:
1. File nonresident tax return Form 1040NR. You can also deduct moving expenses. Use form 3903.

2. File joint return as residents (Form 1040). You will get standard deduction of $11,400 and exemptions ($3,650 each) for both of you. To file joint return, you must wait till you complete SPT in 2010. http://taxipay.blogspot.com/2008/04/substantial-presence-test.html

You must both declare your worldwide income for 2009. If you have any foreign income, and on that income you paid taxes in the foreign country, then you can claim foreign tax credit (Form 1116) or you can use Foreign Earned Income Exclusion (Form 2555). http://taxipay.blogspot.com/2008/03/us-citizen-or-resident-with-foreign.html

You will complete forms W7 (application for ITIN) for your spouse and attach with your tax return. You can also deduct moving expenses. Use form 3903.

If I file 1024NR. Then I also claim for Social Security Tax & Medical Tax

No, your income is subject to SS tax and Medicare tax as you have work visa.

Hello Dear, I'm here on J1 visa and want to change in L1 visa. Do u know anything about that if know please advise me. I really appreciate your advide

Kheri:
Please post your question as a new topic.