IN this website

http://www.thetaxguy.com/residency.htm

The tax guy says...

Dual-Status Aliens

Note on page 7 of Publication 519 under Dual-Status Aliens that you could be both a nonresident alien and a resident alien in the same year. That means your tax return becomes more complicated. Publication 519 explains how to figure the tax beginning on page 25. Here are the most common circumstances of dual status:

• When you enter the country and receive permanent residency status (receive a Green Card) during the year of arrival
• When you hold a J, F, M, or Q visa the first part of the year and receive permanent residency status during the year
• When you hold a J, F, M or Q visa during part of the year, but later change to an H visa or other status eligible to use the substantial presence test, and pass the test
• When you leave the United States permanently during a year in which you qualify as a tax resident, but only if certain conditions apply. (See Last Year of Residency on page 8 of Publication 519.)

So according to this (point 3) we have to file as dual status right?

You left out an important sentence:

You might be a dual-status alien if you permanently left the U.S. during the year.

DR Carter was clear in his email to me. Conversion from F-1 to H-1 status by itself does not make you liable for the dual-status tax return.

You CAN file that way if you want (in fact, I did so with a client earlier this year because it was the most advantageous wasy to file).

However, In my opinion, you are not required to file a dual-status return unless you physically enter or leave the country.