Children who are claimed as dependents on a U.S. tax return, and who aren't eligible for an SSN, need their own ITIN. The process uses the same Form W-7, but the required documents are different for minors.
Documents required for a child's ITIN
A child's passport alone is sufficient if it has a date of entry into the U.S. stamped (for dependents who are required to be physically present). Without that, you'll typically need the child's birth certificate plus one other document, such as medical or school records, since a child may not have a driver's license or other adult-style ID.
Who signs the application
A parent or court-appointed guardian signs Form W-7 on behalf of a child under 18. If both parents have legal custody, either one can generally sign.
Related situations in the family
See the full rules for dependents and spouses if you're applying for more than one family member, or check ITIN numbers for dependents if you already have the ITIN and need to use it correctly on your return.
