In order to file your tax return, you typically need to provide a Taxpayer Identification Number (TIN) or Social Security Number (SSN). However, if you are not eligible for an SSN and do not have a TIN, you can apply for an Individual Tax Identification Number (ITIN), in order to file your tax return.

Most people in the US will have either an SSN or TIN. However, in special circumstances, for instance, you immigrated to the US and have applied for legal residency or work status and are awaiting a decision, you may need to request an ITIN in order to file a tax return.

An ITIN has other benefits — in addition to helping you file your tax return and allowing you to claim tax credits, you can also use it as a valid form of identification, to open a bank account, and to buy health insurance.

To apply for an ITIN when filing your tax return, you’ll complete IRS Form W-7, Application for IRS Individual Taxpayer Identification Number. Complete this form and send it to the IRS, along with your tax return, and copies of your identification and foreign residency status. An adult can also request an ITIN for a dependent under 18.

You’ll need to mail in these documents or tax forms to the IRS. You cannot e-file them. You can also visit an IRS Taxpayer Assistance Center to get help preparing your W-7 or find an agent through the VITA (Volunteer Income Tax Assistance) program to help you file your ITIN request and tax return.