An Individual Taxpayer Identification Number, or ITIN, is a nine digit number the IRS issues to people who need to file or be included on a US tax return but are not eligible for a Social Security number. It always begins with a 9, it exists purely for federal tax purposes, and for millions of people it is the key that unlocks filing taxes, claiming dependents, opening certain bank accounts, and building a documented financial life in the United States.
Who needs an ITIN
You need an ITIN if you have a US tax obligation and cannot get a Social Security number. The most common situations we see at our Naperville office: nonresidents with US income who must file a return, residents who meet the tax filing tests but are not SSN eligible, spouses being included on a joint return, dependents being claimed on a return, and people named on tax treaty claims or certain withholding documents. If you are eligible for a Social Security number, you cannot get an ITIN, and the IRS will reject the application.
What an ITIN does and does not do
An ITIN lets you file federal and state tax returns, be claimed on a return, receive certain tax credits where the rules allow, and satisfy banks or lenders that ask for a taxpayer identification number. It does not authorize you to work in the United States, does not provide Social Security benefits, and does not change your immigration status. It is a tax processing number, nothing more and nothing less, and being precise about that protects you.
How to apply: the three routes
Every ITIN application runs through Form W-7, usually attached to the federal tax return that creates the need for the number. What differs is how your identity documents are handled, and this is where the three routes matter.
First, you can mail your application to the IRS with your original passport or other identity documents. The IRS holds your originals while it processes the application, which routinely takes two months or more. Being without a passport for that long is the single biggest complaint we hear about the process.
Second, you can book an appointment at an IRS Taxpayer Assistance Center, where staff can verify certain documents in person. Appointments are limited and often booked out weeks ahead, especially during filing season.
Third, you can apply through a Certified Acceptance Agent, or CAA. A CAA is authorized by the IRS to verify your identity documents and certify them with the application, which means your passport never leaves your hands. Our founder is a CAA, and this is exactly why families choose the CAA route: one appointment, documents verified on the spot, application prepared correctly, and everything tracked until the number arrives. Read more about our ITIN application service or what a Certified Acceptance Agent does.
What documents you need
The IRS accepts a specific list of identity documents, and the passport is the only one that proves both identity and foreign status on its own. Without a passport, you need two documents from the approved list, such as a national identification card, birth certificate, or visa. Documents must be originals or copies certified by the issuing agency; notarized copies are not accepted. A CAA appointment resolves most document questions on the spot, which is why rejected do-it-yourself applications so often become CAA appointments the second time around.
How long it takes
Plan on roughly seven weeks for the IRS to process an ITIN application, and longer during filing season or for applications from abroad. The clock only starts when the application is complete and correct. An application that bounces for document problems or missing information starts the wait over, which is why getting it right the first time matters more than any other part of the process.