I entered on f-1 visa in aug 2006,
Started opt in dec 2007 - valid till dec 08
Have an approved h-1 starting/valid from october 1st 2008

Started working from august 08, h-1 might start october
What will be my tax residency status?

2 months work on opt then on h-1 b
Am i subject to ss taxes and medicaid taxes

Am i eligible to recive the 5750 india tax treaty exemption i received as a student.

Any links to a free tax calculator are highly appreciated.

Also is per-diem taxable?

Thanks a ton in advance for the expert answers

You will file as a non-resident alien for 2008.

You become liable for Social Security and Medicare taxes thed day your H-1B visa becomes effective.

You SHOULD be able to claim the standard deduction under the U.S.-India Tax Treaty.

The website below has a tax calculator:

2008 Online Non Resident Tax Software - File Form 1040NR-EZ, Form 8843, Form 843, Form W-7, Form 1040NR, International Student Taxes, Non Resident Taxation F1,J1,H1B Visa Taxes, Where to File, Instructions, Mailing Address, Income Tax Forms

Perdiem CAN be taxable. It depends on how the per diem is paid and accounted for on the employer's books.