This document contains final regulations under sections 6051 and 6052 of the Internal Revenue Code (Code). To aid employers' efforts to protect employees from identity theft, these regulations amend existing regulations to permit employers to voluntarily truncate employees' social security numbers (SSNs) on copies of Forms W-2, Wage and Tax Statement, that are furnished to employees so that the truncated SSNs appear in the form of IRS truncated taxpayer identification numbers (TTINs). These regulations also amend the regulations under section 6109 to clarify the application of the truncation rules to Forms W-2 and to add an example illustrating the application of these rules. Additionally, these regulations delete obsolete provisions and update cross references in the regulations under sections 6051 and 6052. These regulations affect employers who are required to furnish Forms W-2 and employees who receive Forms W-2.