What an ITIN is
An ITIN is a nine-digit tax processing number the IRS issues to people who need a US taxpayer identification number but are not eligible for a Social Security Number. It exists for federal tax purposes only. It does not authorise work in the US, it does not change immigration status, and it is not identification outside the federal tax system.
For a non-US founder it is the first layer of everything else. Before a US company can be tied to you, before a bank can identify you in its own systems, before any credit file can exist, the US system needs a number that means you. That is the ITIN.
Who needs one
- A non-US founder who owns or is forming a US company and must be identified for US tax reporting.
- A non-US person with a US filing or reporting requirement who cannot get a Social Security Number.
- Anyone who intends to open US banking relationships and build a US credit profile as a non-resident. The ITIN is the first document a bank or card issuer will ask a non-US founder for.
If you have a Social Security Number you do not need an ITIN; the two are alternatives, not a pair.
ITIN, SSN and EIN: three different numbers
All three are US tax identifiers. The Social Security Number identifies US citizens and residents. The Employer Identification Number identifies a company. The ITIN identifies an individual who cannot get an SSN. A non-US founder with a US company usually ends up holding two of them: an EIN for the company and an ITIN for themselves.
Confusing them is the most common early mistake. An EIN does not identify you, and it does not let a bank open a personal relationship with you. The ITIN does. If the IRS has already rejected an application, the CP567 guide explains why that happens and how the second one gets accepted.
How the application works
The application is Form W-7, filed with supporting documents that prove identity and foreign status. The IRS lists three ways to submit it: by mail to its Austin service centre, in person at an IRS Taxpayer Assistance Center in the US, or through the agents and volunteer sites the IRS authorises. Applying directly through the IRS is free; the IRS itself does not charge for the number.
The difficulty is rarely the form. It is the stack of documents behind it: a copy that is not certified the way the IRS requires, a missing letter, the wrong reason code. Most rejections come from that stack. Our ITIN service exists for that reason: we prepare the W-7, check every document against the IRS requirements, file the application and track it until the number arrives.
What the IRS accepts
A valid passport is the one document the IRS accepts on its own to prove both identity and foreign status. The IRS lists twelve other documents that can be combined instead, but for a founder with a passport, the passport is the route.
You will also need a reason for applying. Founders we work with usually file because of a US business or a US reporting requirement, and picking the right box matters. An address where the IRS letter can reach you completes the picture, because the number arrives by post.
How long it takes
The IRS sets the timing, not the preparer. Its published guidance is to allow around seven weeks for a decision, and nine to eleven weeks during the January 15 to April 30 peak or when applying from outside the US (IRS figures as of February 2026). A clean file does not speed the IRS up, but a rejected one adds the whole cycle again, which is why the checking matters.
Does it expire?
An ITIN stays valid as long as it is used. If it is not included on a federal return for three consecutive tax years, it expires at the end of that third year and has to be renewed before it can be used again on a return.
What the ITIN does not do
- It is not a credit card, a bank account or an approval. It puts you on the map with the IRS. It does not make a bank say yes.
- It is not a work permit, a visa or immigration status.
- It is not an EIN and it is not an SSN.
- It is not tax advice. What you file with it is between you and your CPA.
This guide describes how the US system works for non-US founders and how we build within it. It is not tax, legal or immigration advice; your CPA or attorney answers those questions for your situation.