Assuming my Mexican mother-in-law qualifies for an ITIN, is it too late to apply for an ITIN in time for our 2017 tax return? She meets the definition of dependent for us

[parthenophilast]

Please no need for detail on who qualifies; that info is everywhere. My question is about timing. My mother -in-law does not have to file a tax return, so this is just for claiming her as a dependent.  I'm assuming that, if we obtain an ITIN for her, it can't be retroactively applied toward an amended 2016 return, but I was hoping we could claim an exemption for the 2017 taxes. Thanks 

[CherylW · Accepted solution]

This, from IRS Instructions for Form W-7:

To receive an ITIN for the first time. If you’re applying for a new ITIN, complete and attach Form W-7 to your tax return when you file the tax return for which the ITIN is needed.

You can’t electronically file (e-file) a return using an ITIN in the calendar year the ITIN is assigned.

So you'll have to mail the return for the first time when you claim your mother-in-law:

Internal Revenue Service

ITIN Operation

P.O. Box 149342

Austin, TX 78714-9342

Instructions for W-7, Application for ITIN

Form W-7

Wait to file your amended 2016 until you receive her ITIN.  I can't find anything on whether you can amend for a retroactive W-7.  I'm thinking not, but you can try.