She cannot file a zero return to get the ITIN.
You can get the ITIN when you file a joint tax return ...
To get an ITIN, what you
will do is complete the return, and print it out. To print without a SSN where
hers would go, when you get the message that says "There are errors
in your return. Continue?" If you click Yes it will print. If that does not work
you may have to enter a made-up SSN and then white out or cross it out once you
print it. You will NOT e-file your return, you will select that you are mailing
it.
You will also print out a
form W-7 and gather any of the required documentation, put that together with
your return, and mail it to the specified address. The IRS will then process
your return and issue your wife an ITIN.
Here is more information on
the ITIN and the process: https://www.irs.gov/Individuals/General-ITIN-Information
