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, 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 for Forms W-2 and W-3 for details.