The petition request number for H1B is also known as the H1B case number or the H1B EAC case number. It is a 13-digit code assigned to every visa application, including the H1B, and is broken up into four parts that represent the location, year, day, and case number for each applicant. The H1B petition number is typically assigned by USCIS and starts with three alphabets like WAC or EAC based on where it was filed. The first three letters indicate where the H1B petition was filed, and the next two digits represent the fiscal year in which USCIS received the petition. The next three digits represent the computer workday on which the receipt was processed and the fee was taken. Finally, the last five digits represent the unique case number assigned to each application.