ITIN 설명서를 보니 제가 달았던 댓글과 달리 사무실에 방문해서도 신청할 수 있다고 하네요. 설명서 상의 내용은 아래와 같습니다.
By mail.
Mail Form W-7, your tax return (or other documents required by an exception), and the documentation described in item (3) and listed in the chart under How To Apply, earlier to:
Internal Revenue Service
ITIN Operation
P.O. Box 149342
Austin, TX 78714-9342
CAUTION: Do not use the mailing address in the instructions for your tax return.
Private delivery services.
If you use a private delivery service to submit your Form W-7, use the following address:
Internal Revenue Service
ITIN Operation
Mail Stop 6090-AUSC
3651 S. Interregional, Hwy 35
Austin, TX 78741-0000
In person.
You can apply for an ITIN by bringing your completed forms and documentation to any IRS Taxpayer Assistance Center in the United States or IRS office abroad. Designated IRS Taxpayer Assistance Centers will be able to verity passports and National ID documents and return them immediately. Information on our overseas offices can be found in Pub. 1915 or at IRS.gov.
Through acceptance agent.
You also can apply through an acceptance agent authorized by the IRS. An acceptance agent can help you complete and file Form W-7. To get a list of agents, visit IRS.gov and enter “acceptance agent program” in the search box at the top of the page.