Stop the Misuse of ITINs Act of 2007 - Amends the Internal Revenue Code to require the Secretary of the Treasury to: (1) notify the Secretary of Homeland Security of any employer tax return which shows wages paid to an employee who is not authorized to be employed in the United States; and (2) provide a written notice to the employer and employee involved that such employment is illegal and must be terminated within 30 days after the date of said notice. Allows any employee who receives a notice to contest such notice and provide documentation substantiating such employee's claimed authorization to work in the United States.