It depends on the type of contribution. Generally, these withholding rules apply: Social Security (FICA) and Medicare Federal income tax Employee elective salary deferrals – pre-tax Yes No Employee elective salary deferrals – Roth Yes Yes Employer matching and nonelective contributions No No See Publication 15-A PDF, Employer’s Supplemental Tax Guide, for details and special rules for plans sponsored by government or nonprofit organizations. Form W-2 reporting for retirement plan contributions Box 1 (Wages) – Don’t include pre-tax contributions made under a salary reduction agreement. Box 3 & 5 (Social Security and Medicare wages) - Include all employee pre-tax, after-tax and designated Roth contributions. Box 12 (Codes) - Enter appropriate codes to show elective deferrals and designated Roth contributions to different plan types. Separate codes indicate excess elective deferrals. See the Code Reference Chart in the form instructions. Box 13 (Checkboxes) – Check the box if the employee was an active participant in a retirement plan. See the decision chart in the form instructions for help making this determination. Box 14 (Other) – You may enter the amount of employer matching and nonelective contributions made to the plan and the amount of voluntary or mandatory employee after-tax contributions (not including Roth). See the Instructions PDF for Forms W-2 and W-3 for details.