It is always a difficult problem to determine who is an employee or contractor and preventing those hired as contractors from being employees, or vice versa. The extent to which the worker has unreimbursed visit expenses.
Independent contractors are more likely to have unreimbursed expenses than employees.
Employers should not routinely approve reimbursement requests for business-related expenses, because this could be used as evidence of employee status. The extent of the workers' investment. One of the most significant investments is office or work space. The extent to which the worker makes services available to the relevant market. If the worker does the same work for other companies, it's a key indicator of independent contractor status.