A control number on a W-2 form is a unique identifier assigned by the Social Security Administration (SSA) to each W-2. It is used to match the W-2 with the SSA’s records and to help prevent fraud. For example, if you receive two W-2s with the same control number, you should contact the SSA to report a potential error.
The control number is an important part of the W-2 form because it helps to ensure that the information on the form is accurate and complete. It can also be used to track down errors or fraud. In 2012, the SSA implemented a new system for generating control numbers that is more secure and difficult to counterfeit.