I arrived in US on May 5, 2006 on L-1 visa with my wife (L-2). My payroll with the company started in June 2006, because there was a bumpy transition from payroll in my country of origin to US office payroll. I stayed in the US until September 23, 2006 where I was sent on a business trip to my country of origin and returned to US on January 22, 2007.

Should I file as Resident or Non-Resident alien in this case? Any help is greatly appricated, thank you.

If you file jointly with your wife, you BOTH can file as resident aliens for all of 2006, but you MUST declare ALL world-wide income.

You can also file as a non-resident alien, but then you will NOT be able to claim your wife as a dependent.