The receipt number is one of the most commonly used numbers, by immigrants and lawyers alike, to track the progress or identify a particular immigration case or filing.
These receipt numbers start with three letters and follow by a series of numbers, for example EAC-06-123-45678. Here is how to understand what the numbers mean.
The first three letters indicate the USCIS service center which is processing the petition, as follows:
- EAC - Vermont Service Center;
- WAC - California Service Center;
- LIN - Nebraska Service Center; and
- SRC - Texas Service Center.
The next two digits represent the fiscal year in which USCIS received the petition. In the example above, “06″ means that the petition was received by USCIS during Fiscal Year 2006. The next three digits represent the computer workday on which the receipt was processed and the fee was taken. Finally, the last five digits are used to identify uniquely the petition filed.
Source: http://www.cilawgroup.com/news/2008/07/21/receipt-numbers-explained-lin-src-eac-wac/