I filed my 2005 tax returns as "married filing separately", my wife had not yet joined me in the US.

My wife has joined me since and has her ITIN, and the question is, can I amend my 2005 tax return to change filing status as "married jointly" to take advantage of the deductions?

(My wife only joined me in the US in 2007, does that make it impossible to so amend ?)

Yes, you can amend. However, you have to do it prior to April 15, 2009.

Thank you, very much IntlTax.

I was sort of disappointed yesterday when the tax advisor I went to at H & R block said this couldn't be done - according to her - my wife had to have been there in US in 2005/2006 to amend.

I will try another advisor.

If you have H1-B in 2005, then you can choose to file joint return even if your wife has never been to the US.
Contact [email protected] to do your return.