contribution Employee made to 401 not corporation where does it go on the w2 and will it be taxed as excess contributions

[accomacktax]

Employees own a S corp they contributed to their 401k not the employer does it go on the w-2 and if so where  I can put the roth in box 12 coded as AA but what about the 401  employee contribution that just goes on  schedule 1 of their tax return correct and they are high wage earners so  they will be taxed  as excess contributions on the 1040

[DavidD66]

Employee contributions to a 401(k) are reported in Box 12 of Form W-2 with Code D.  Those contributions/elective deferrals have to be run through payroll.  While the amount withheld and contributed to the 401(k) is not subject to federal and state income tax it is subject to Social Security and Medicare and reported in boxes 3 and 5 of the W-2 as applicable.  Being a high wage earner does not make 401(k) contributions taxable, but if the plan is "Top Heavy" then highly compensated employees may be limited to the amount they can contribute.  Excess contributions are subject to an excise tax each year until removed.  For additional information see the following IRS web page:  401(k) Plans