When filing the Adjustment of Status application (I-485), the foreign national can also apply for an Employment Authorization Document (EAD) and work on the basis of the EAD. While the cost of the application for the EAD are included in the cost of the Adjustment of Status application, separate applications must be submitted for each benefit. Normally, these applications are prepared by the attorney who files the I-485.
Once the EAD card has been issued, one can work on the basis of the EAD instead of the underlying nonimmigrant status (such as H-1B). The employment restrictions that apply to the nonimmigrant status do not apply when one is working on the basis of the EAD. Note that the EAD has an expiration date. If it expires before the green card is issued, it should be renewed. Please discuss this extension with the attorney handling your green card application.
FSIS recommends that, if possible, employees who hold H-1B status maintain their H-1B status while their green card application is pending.