You will be able to file
jointly with your spouse for tax year 2015 even if she is not in the USA anytime during 2015. And a spouse is never claimed as a dependent, they are your spouse on a joint return which correctly gets you the personal exemption for each of you.
However you will need
either a social security number (if they are eligible) or a taxpayer
identifying number to include your new spouse on your return. Use IRS
Form W-7 to apply for a Taxpayer Identifying Number. A copy is
here: http://www.irs.gov/pub/irs-pdf/fw7.pdf . You need to attach your federal tax return to the application.
The tax return and W-7 are mailed to:
Internal Revenue Service
Austin Service Center
ITIN Operation
P.O. Box 149342
Austin, TX xxxxx-xxxx
When the
number is issued you will receive a notice in the mail and the
federal return will be forwarded for processing automatically. If you
will need to file a state return as well and you have not gotten the ITIN by
4/15 then file a state extension and complete the return when you get the
number.
Also: "You may also apply using the services of an IRS-authorized
Acceptance Agent or visit an IRS Taxpayer Assistance Center in lieu of mailing
your information to the IRS in Austin. TACs in the United States provide
in-person help with ITIN applications on a walk-in or appointment basis.
Applicants outside the United States should contact an overseas IRS office to
find out if that office accepts Form W-7 applications. The IRS's ITIN Unit in
Austin issues all numbers by mail."
