Your spouse does not need to apply for a work permit once they are admitted as an immigrant with their immigrant visa or have already been approved for adjustment to permanent resident status. As a legal permanent resident, your spouse should receive a Permanent Resident Card (commonly referred to as a "Green Card") that will prove that your spouse has a right to live and work in the United States permanently. If your spouse is now outside the United States, your spouse will receive a passport stamp upon arrival in the United States. This stamp will prove that your spouse is allowed to work until a Permanent Resident Card is created.

If your spouse is in the U.S. and has applied to adjust to permanent resident status (by filing USCIS Form I-485, Application to Register Permanent Residence or Adjust Status), they are eligible to apply for a work permit while their case is pending. Your spouse should use Form I-765 to apply for a work permit.