I currently reside in FL. I got married in December 2018. I would like to file as married filing jointly but for that i need to get an ITIN for my wife who is a non-resident alien and lives overseas. I got a signed W7 from her and about to file for an ITIN number. My question is, can i use her ITIN as soon as it is issued? I do not owe any taxes but i expect my refund to go up if i file jointly with my wife. Currently without my wife, i qualify as head of the household claiming my mom and dad. So should i file for an extension, file for my wife's ITIN, and use it when it is issued to file as MFJ? Any advise will be appreciated. Thanks!