How Do You Apply for an ITIN?
Getting an ITIN isn’t a matter of filling out a short form and waiting a few days. It’s a documentation-heavy process built around proving exactly who someone is, which is part of why applications often take longer than people expect.
The short answer
Applying for an ITIN generally means filing Form W-7 along with documents that prove identity and foreign status, most commonly a passport, and typically attaching it to the federal tax return that creates the need for the number. The application can be submitted by mail, through an IRS-authorized acceptance agent, or in person at certain IRS offices, and processing commonly takes several weeks.
What the application requires
The W-7 asks for basic identifying information along with the reason an ITIN is being requested, since the number serves several different purposes depending on who’s applying. Alongside the form, the applicant needs documentation that establishes both identity and foreign status. A current passport can satisfy both requirements on its own; without one, applicants typically need to combine two or more other documents, such as a national identification card and a birth certificate, from an IRS-approved list.
Common reasons applications get delayed
- Missing or expired documents. Identity documents that have expired, or that don’t clearly show a photo and current address, are a frequent cause of rejection.
- Incomplete reason codes. The W-7 asks the applicant to check a box explaining why an ITIN is needed, and choosing the wrong category, or leaving supporting detail out, can trigger a request for more information.
- Return not attached when required. Most applications need to be submitted along with the tax return that creates the filing need, and a missing return is one of the more common reasons a package gets sent back.
Ways to submit the application
Original documents can be mailed directly to the IRS, but many applicants prefer not to send a passport through the mail. Two alternatives exist: using an IRS-authorized acceptance agent, often a tax preparer or enrolled professional trained to certify documents without forwarding the originals, or visiting a designated IRS Taxpayer Assistance Center in person, where documents can be verified on the spot.
Timing relative to a filing deadline
Because an ITIN application is usually filed together with a tax return, and processing can take a while, timing matters. Someone applying close to a filing deadline may need to request more time to file rather than rush an incomplete application, since a rejected or incomplete W-7 package can mean starting the documentation process over.
What happens after submission
Once a complete package reaches the IRS, processing generally takes several weeks, longer during the busiest stretch of filing season. The agency reviews the identity documents, matches them against the reason claimed on the form, and either issues the number, requests additional information, or rejects the package outright if something doesn’t line up. Original documents sent by mail are typically returned once processing finishes, though the exact turnaround for that return shipment can add extra time beyond the ITIN itself being issued.
After the number is issued
Once assigned, the ITIN becomes the number used on that return and future ones, in the same field where an SSN would otherwise appear. It’s worth keeping a record of the number separately from the return itself, since it will be needed again for future filings, and, as covered in what an ITIN is and who needs one, the number can lapse if it goes unused for several consecutive years, which would mean going through a similar renewal process later.
The bottom line
An ITIN application is really an identity-verification process wrapped around a tax form, and most delays trace back to documentation rather than the form itself. Gathering complete, current documents before submitting, and choosing a submission method that fits the applicant’s comfort with mailing original paperwork, is generally the biggest factor in how smoothly the process goes.