The receipt number is the unique case number the USCIS assigns to each applicant after receiving their petition. It is a very important number as it will be used to track the progress of your petition during the USCIS phase.
How to read the receipt number?
The receipt number is normally 13 digits start with 3 letters and followed by 10 numbers contains 4 part. For example: NSC 17 023 40299 means
USCIS Service Center
The first three letters indicate which service center receives and processes your application or petition. They are:
|VSC/EAC||Vermont Service Center/Eastern Adjudication Center||CT, DE, ME, MD, MA, NH, NJ, NY, PA, PR, RI, VT, VA, VI, WV, DC|
|NSC/LIN||Nebraska Service Center/Lincoln Service Center||AK, CO, ID, IL, IN, IA, KS, MI, MN, MO, MT, NE, ND, OH, OR, SD, UT, WA, WI, WY|
|TSC/SRC||Texas Service Center/Southern Regional Center||AL, AR, FL, GA, KY, LA, MS, NM, NC, SC, OK, TN, TX|
|CSC/WAC||California Service Center/Western Adjudication Center||CA, NV, AZ, HI, GU|
|YSC||Potomac Service Center|
|NBC/MSC||National Benefits Center|
The next two digits indicate the fiscal year that your petition was received by USCIS. The government's fiscal year starts on October 1 and ends on September 30.
The next three digits represent the computer workday that they start working on your case. It's the day they cash your check or money order. For example, 023 means they opened your case on the 23rd computer workday of the current fiscal year.
The last five digits is the number identifying the case receipt order. Normally, applications with few different petitions will have the case numbers in sequence.