My ITIN letter
Here's what it says: "If you become a US resident or a US citizen, you will probably be eligible to get an SSN. If so, you must then apply for an SSN from the Social Security Administartion and start using that number for tax purposes instead of your ITIN. When you receive an SSN, please send a copy of your social security card, along with a copy of this notice to the address listed above, so that we can update our records."
The address in the left corner above:
"Department of Treasury
Internal Revenue Service
Philadelphia, PA 19255"
"For assistance, call us at: (215) 516-4846
or you may write us at: P.O. Box 447
Bensalem, PA 19020"
Hope this helps.