USCIS Receipt Numbers Explained: WAC, LIN, SRC, IOE, and EAC

A USCIS receipt number follows a consistent 13-character format: three letters identifying the service center, followed by a two-digit fiscal year, followed by an eight-digit sequential case number. The three-letter prefixes each correspond to a specific processing location. WAC indicates the California Service Center, LIN indicates the Nebraska Service Center, SRC indicates the Texas Service Center, EAC indicates the Vermont Service Center, and IOE indicates a case processed through the USCIS Electronic Immigration System, the agency's online filing platform, which has become increasingly common as USCIS expands digital filing across form types. Seeing an IOE prefix generally means your case was filed online rather than on paper, which does not change your legal rights but does mean you should be checking your USCIS online account rather than expecting everything to arrive strictly by mail.

Historically, each service center specialized in certain form types and geographic regions, though USCIS has increasingly shifted volume between centers to balance workloads, so the center your case lands at is not always predictable from your location alone. The California and Vermont service centers have both handled significant H-1B volume for years, alongside other employment-based petitions, while the Nebraska and Texas centers handle a broad mix of family-based and employment-based filings. The rise of the IOE prefix reflects USCIS's broader modernization push, since forms filed through the online portal are routed and tracked through the electronic system regardless of which physical service center ultimately adjudicates them. If your receipt number does not match the center you expected based on older guidance, that is normal; workload-balancing transfers between centers happen routinely and do not indicate a problem with your case.

Your receipt number is the key you enter into the USCIS Case Status online tool to check where your petition or application currently stands. Entering it correctly, all 13 characters, no spaces or dashes, pulls up the current status along with a plain-language description and often the date of the most recent update. Beyond the basic case status page, the same receipt number can be linked to a USCIS online account, which for many form types now provides more detailed tracking, document upload capability, and the ability to receive text or email notifications automatically whenever your case status changes, rather than requiring you to manually check the site. Keep your receipt notice, the I-797C that contains this number, in a safe and easily accessible place, since you will need it not just for status checks but for many downstream steps like scheduling biometrics or responding to a Request for Evidence.

"Case Was Received" means USCIS has logged your filing and it is awaiting assignment for review; this is typically the first status you will see and can last anywhere from days to several weeks depending on the form type and current volume. "Biometric Services Appointment Was Scheduled" applies to certain form types requiring fingerprints and photos, most commonly green card and EAD applications rather than H-1B petitions themselves. "Case Is Being Actively Reviewed By USCIS" indicates an officer has picked up your file and is working through eligibility. "Request for Additional Evidence Was Sent" or "Response To USCIS' Request For Evidence Was Received" indicate an RFE has been issued or your response has been logged. "Case Was Approved" is the outcome most petitioners are hoping for and typically triggers mailing of an approval notice within one to two weeks. Average wait times vary substantially by form type: H-1B petitions filed with premium processing get a decision within 15 calendar days, while standard processing for the same form can take several months, and green card-related forms like the I-485 can take many months to over a year depending on the service center and category.