I am in the US from Dec 2008, and this year will be considered as resident alien for the tax purpose, as even my paycheck shows deduction of SST. My wife lives with for last two year and are on F1. For 2015 tax return filing, can I apply for her ITIN, and then claim her dependent as well as file jointly.

FYI, you should have been reporting as a resident starting with the 2013 tax return, because Dec 2008 counted as a full year in your 5-year period for your F-1 visa.

Below are the two BEST alternatives that allows you to file jointly while applying for an ITIN for your wife. If you were married in 2013 and 2014, you can then amend those years returns to probably get more refund.

If you wish to use my professional service, contact me at the email address in my profile.

BEST ALTERNATIVE: The IRS also has Tax Assistance Centers through which you may be able to have the passport verified as genuine, then submit the tax return and Form W-7 IN PERSON to be forwarded to the ITIN Processing Center in Austin, Texas for processing , without having to get the photocopies certified by your home country consulate.

You go to the TAC with your wife, her passport, the SIGNED Forms W-7, and the completed and SIGNED tax return with your W-2s.

The IRS official verifies the passports, asks a few questions, completes the certification paperwork, checks the Forms W-7 and tax return, then returns the passports with a receipt for the tax return and Forms W-7, which is sent to Austin, Texas for processing.

You leave the TAC with your wife, the passport and a receipt for the Forms W-7 and the tax return.
You would get the ITIN about six weeks after you left the TAC.

The tax returns are NOT processed at Austin, Texas, but rather forwarded to the regional IRS centers for processing, so the refund will come about one month AFTER you get the ITIN letters.

The list of the TACs are at the link below:

http://www.irs.gov/uac/TAC-Locations-Where-In-Person-Document-Verification-is-Provided

SECOND ALTERNATIVE. I am a Certifying Acceptance Agent, and I can certify the passport if the TACs are not close.

You would mail the passport and the SIGNED Form W-7 and SIGNED tax return to me. I would contact you via SKYPE, conduct a brief interview with your spouse, certify the passport, attach the certification to the SIGNED W-7 and sign both documents. I would also sign the tax return, then paperclip the W-7 with certification to the tax return, and then mail them to the IRS ITIN Processing Center in Austin, Texas.

The passport I would mail BACK to you via tracked PRIORITY MAIL, so the passport would be out of your possession for about a week.