Check your IRS Notice CP565, which was mailed when your ITIN was assigned
Look at any prior IRS notices or letters that show your ITIN
Review your previous tax returns, W-7 application copy, or tax preparation records
Check documents from your tax preparer or accountant
Call the IRS ITIN hotline at 1-800-908-9982
If you cannot locate it, request help from the IRS or your tax professional to verify it