Knowing how the IRS defines something is often key to understanding how to or whether to file or report; as well as going a long way toward helping you handle B-Notices, Proposed Penalty Notices or Audit situations. Today, let's examine what exactly the IRS means when it speaks of a "missing TIN" and what you should be doing in response. 

First off, TINs can be a Social Security Number (SSN), an Employer Identification Number (EIN), or an Individual Taxpayer Identification Number (ITIN). SSNs are assigned by the Social Security Administration: EINs and ITINs are assigned by the IRS. Now, according to the IRS if a TIN is not provided or is obviously incorrect, it is considered missing. TINs lacking nine numerical digits or containing alpha characters are considered incorrect. So what should you do with a payee account missing its TIN?

Hopefully, you completed an initial solicitation for the payee TIN using Form W-9. If not, and you are making payments you had better be backup withholding until that payee name and TIN is provided. In addition, you better be asking regularly. How often? Well, if a TIN is not received as a result of the initial solicitation then you need to solicit again by December 31 of the year in which the account is opened (for accounts opened before December) or by January 31 of the following year (for accounts opened the preceding December). From there, if a TIN still has not been forthcoming, you need to ask again the following year.

If during this process a TIN is received from the payee, then stop backup withholding and include it on any future information returns filed for that payee.