As a payroll company that specializes in adding ITIN workers to payroll, we hear this question all the time: "How can we add people as W-2 employees if they're not allowed to work?"
The simple answer is, you can't.
The bottom line is...
It doesn't matter if someone has an SSN (Social Security Number) or an ITIN (Individual Taxpayer Identification Number); what really counts is if they can fill out the I-9 form.