The spouse may start employment after obtaining a valid work-authorizing status and suitable evidence. Valid L-2S status may arise through admission or an approved change of status, depending on the facts. Review visa, travel or filing steps individually; the principal’s approval notice alone does not authorize the spouse’s work.
Keep the two starts separate on the calendar
The transferring employee's start date and the spouse's are different events, and treating them as one leads to commitments the household cannot meet. Approval, a visa where required, admission, and lawful employment are distinct stages for each person. If a role is offered to the spouse before the family travels, discuss the sequence with counsel before agreeing to a start date.
Put both starts on one calendar with the intervening steps written between them, since the household's two most important dates otherwise get discussed in separate conversations. For the principal: approval, any visa step, admission, assignment start. For the spouse: admission or an approved change of status, the status evidence in hand, then employment.
Where an offer to the spouse arrives before the family travels, tell counsel before agreeing a start date, because a date accepted on optimism is considerably harder to move than one negotiated on facts. Review the calendar again after admission.