Social Security Wage Base

For the Old Age, Survivors and Disability Insurance (OASDI) tax or Social Security tax in the United States, the Social Security Wage Base (SSWB) is the maximum earned gross income or upper threshold on which a wage earner's Social Security tax may be imposed. The Social Security tax is one component of the Federal Insurance Contributions Act tax (FICA) and Self-employment tax, the other component being the Medicare tax. It is also the maximum amount of covered wages that are taken into account when average earnings are calculated in order to determine a worker's Social Security benefit.

In 2017, the Social Security Wage Base was $127,200 and the Social Security tax rate was 6.20% paid by the employee and 6.20% paid by the employer. A person with $10,000 of gross income had $620.00 withheld as Social Security tax from his check and the employer sent an additional $620.00. A person with $130,000 of gross income in 2017 incurred Social Security tax of $7,886.40 (resulting in an effective rate of approximately 6.07% - the rate was lower because the income was more than the 2017 "wage base", see below), with $7,886.40 paid by the employer. A person who earned a million dollars in wages paid the same $7,886.40 in Social Security tax (resulting in an effective rate of approximately 0.79%), with equivalent employer matching. In the cases of the $130k and $1m earners, each paid the same amount into the social security system, and both will take the same out of the social security system.

The Congressional Budget Office considers the employer share of taxes to be passed on to employees in the form of lower wages that would otherwise be paid, and counts them as part of the employees’ tax burden. Self-employed individuals pay the entire amount of applicable tax.

When an employee works for several different companies during a tax year, his or her Social Security deductions could exceed the cap, because each employer may not know how much the employee has already paid in Social Security tax in other jobs. The Social Security tax coverage will be calculated on his or her personal return, and any excess is applied towards his or her Federal taxes. For example, in 2017 an employee works two jobs (either concurrently or consecutively) paying $70,000 each. Since each employer calculates the social security taxes independently, each employer will withhold 6.2% of the $70,000 employee’s salary, or $4,340, for a grand total of $8,680 -- which exceeds the cap of $7,886.40 by $739.60. The over-payment would be entered on the applicable line of Form 1040 and, assuming the employee did not owe any other Federal taxes, would be refunded to the employee. The employers who each paid $4,340 will not get a refund, since they are not aware that the employee overpaid in aggregate for the year. The government keeps the $818.40 overage. Even if the employers become aware of the overpayment, there is no method to claim the overpayment.

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