In order to get the child tax credit for the Tax Year 2016, SSN/ITIN must be received for the qualifying child by the due date of 2016 tax return i.e., April 18, 2017 (including extensions i.e., October 16, 2017).
You cannot claim the child tax credit or the additional child tax credit on either your original or an amended 2016 return, even if you later get an SSN or ITIN. Also, neither credit is allowed on either your original or an amended 2016 return for a child who does not have an SSN, ITIN, or IRS adoption taxpayer identification number (ATIN) by the due date of your return (including extensions), even if that child later gets one of those numbers.
Note: If you apply for an ATIN or ITIN on or before the due date of your 2016 return (including extensions) and the IRS issues you an ATIN or ITIN as a result of the application, the IRS will consider your ATIN or ITIN as issued on or before the due date of your return.
So, we urge you to file your ITIN application Form before the due date (April 18, 2017). If you are unable to file before due date then take the extension and apply for the ITIN before extension date (October 16, 2017).
Please contact us for more information. Thank you