Depending on the year the notice is for, 6.2% of your wages up to a maximum of somewhere in the neighborhood of $140,000 should be withheld for social security.
If one employer messes up the math or over-withholds, you do not enter this on your tax return. Instead, the employer should give you a refund of the excess social security tax withheld. For example, if you worked the entire year for Employer A and you earn $220,000 and rather than ceasing to withhold Social Security taxes after your wages surpassed the limit, they kept withholding, you would have to get a refund of the excess withheld from your employer.
On the other hand, if you worked for more than one employer and you had social security tax over-withheld because one employer did not know how much the other employer withheld, that would be refunded to you on Schedule 3, Line 11. So if Employer A correctly withheld 6.2% of your $100,000 salary for Social Security and Employer B also correctly withheld 6.2% of your $120,000 salary, it would lead to an over-withholding that would be refunded on your tax return.
Sometimes, you receive 2 W-2s because you transfer within the company or work for two companies that are subsidiaries of the same parent company. In this case, you may get over withheld because of the second situation. However, the IRS thinks you should get it back from the employer because, according to the EIN on the W-2s, they are the same company. Therefore, they will not include it in your tax refund. If that is the situation, you may have to talk to your employer to see if they can get it sorted out.
