The SSN Sequencing Check

The Social Security Administration requires evidence of current, valid work authorization before it will assign a number for work purposes — a job offer letter is not enough. For an H-1B, L-1 or O-1 worker this means the petition must actually be approved and your status must have started; for an F-1 student on OPT it means your Employment Authorization Document must already be in hand. Applying earlier does not speed anything up — it produces a rejection and a second trip to the office.

For a nonimmigrant applicant, the Social Security Administration verifies immigration status electronically with the Department of Homeland Security before assigning a number. That verification is not instant: SSA's own guidance tells new arrivals to wait a stretch of time after entry before applying, so the DHS systems (SEVIS for students, the visa/entry record for workers) have time to reflect the new status. Applying the day you land, before the record has propagated, is the single most common reason for a first rejection.