Deduction from pay are legal in some limited circumstances. I am including a link to the NC Department of Labor's Wage and Hour Division which has a FAQ that discusses deductions and when they are legal. Here is the portion that likely applies to your situation:
"(3) N.C.G.S. §95-25.8(a)(3) - If the amount of a proposed deduction is NOT known in advance, the employer must have written authorization from the employee that is signed before the payday from which the deduction is to be made and that states the reason for the deduction. Prior to actually making a deduction, the employer is required to provide the employee with a WRITTEN NOTICE of the actual amount to be withheld and the employee must be informed in writing of his right to withdraw the authorization. The employee must inform the employer in WRITING if they want to withdraw their written authorization."
Kirk J. Angel is an experienced North Carolina licensed attorney who focuses his practice on employment law. Mr. Angel, who has focused on employment law for more than 15 years, represents clients throughout North Carolina and more information about him is available at www.theangellawfirm.com This response is for general informational purposes and does not constitute legal advice. Additionally, this response does not create an attorney client relationship. If you need legal advice, please contact a lawyer in your state who practices in the appropriate area.