The IRS gives the employer until the end of February to correct a W-2 form. At that time, you can call the IRS, 800-829-1040 and request that an IRS representative initiate a Form W-2 complaint. The IRS will send your employer a letter to provide a corrected W-2 to you within 10 days.
https://www.irs.gov/faqs/irs-procedures/w-2-additional-incorrect-lost-non-receipt-omitted/w-2-additi...