When a new visa applicant creates an online account with USCIS, they will be prompted to create a username and password. Once they have done so, USCIS will assign them a unique account number. This unique 12-digit number is typically a combination of letters and numbers, and it is used to link the individual’s online account to their immigration records
과거 USCIS에서 받은 notice of action 레터에 보시면 12자리 account number 가 있습니다.