To obtain an ITIN, you must complete IRS Form W-7, IRS Application for Individual Taxpayer Identification Number. The Form W-7 requires documentation substantiating foreign/alien status and true identity for each individual.

https://www.irs.gov/individuals/international-taxpayers/taxpayer-identification-numbers-tin

 

How do I file with a W-7?

 

TurboTax doesn't support Form W-7, so there are a few steps you'll have to take to file your return.

You'll need to use TurboTax CD/Download. If you've already begun your return in TurboTax Online, go here to transfer your tax data.

1. Download Form W-7 directly from the IRS, fill it in, and print it out
   • See the IRS instructions
2. Complete your return as you normally would in TurboTax CD/Download, but leave the applicant's Social Security number blank
3. When your return is finished and you get to the File section, ,you'll see a pop-up error message about having no social security number. Select OK.
4. Choose to print and mail your return (you can't e-file without a Social Security number)
5. Mail your return, W-7, and supporting documents to:

Internal Revenue Service

Austin Service Center, ITIN Operations

PO Box 149342

Austin, TX  78714-9342

Instead of mailing, you can also bring your printed, signed return (along with any attachments per the filing instructions, such as W-2s or 1099s), the completed W-7, proof of identity, and foreign status documents to an acceptance agent or an IRS Taxpayer Assistance Center.

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-forms/file-w-7/L2zcFtqtn_US_en_US