Excess Employer Withholding

What Does Excess Employer Withholding Mean?
When one or more employers withhold more than the aggregate maximum amount of Social Security and/or railroad retirement contributions that should have been withheld from a single taxpayer during a taxation year.

Excess employer withholdings are reported on line 67 of Form 1040, and all Copy Bs of the taxpayer's W-2s must be filed with Form 1040.

Investopedia explains Excess Employer Withholding
Excess employer withholdings arise either by human error, when employers make an error in calculating the amount of Social Security or railroad retirement contributions to deduct, or simply from the employee having more than one employer during the year.

If an employee has more than one job during the taxation year, then each employer will calculate Social Security withholdings as if the employee had only one job during the year, which will cause excess withholdings.