What this letter is about This is a valid IRS letter that you may receive. However, due to the sensitive nature of the communication involved, a sample cannot be shown. This letter is sent only to employers to request verification of wages and withholding. What you need to do We included Form 14528, Income/Withholding Fax Verification Reply, with your letter. Please use the instructions in the letter to complete Form 14528 and return the form to the FAX number as requested. The following four fax numbers are used by the IRS to receive information from employers, please verify that one of these numbers appear in your letter before faxing. Fax ending in 8057, 8058, 8059 or 8104. Phone ending in 4430, 4431, 4432 or 4433.