I doubt that they u201cforgot.u201d Plus, thereu2019s no reason for them to amend your W-2 unless they subsequently paid your employee FICA, but thatu2019s more complicated than it may seem.If an employer fails to withhold the employee-FICA tax, the employer remains liable to pay the tax that it should have withheld. But youu2019re liable for it as well. Itu2019s far easier for the IRS to collect it from the employer u2022 the penalty is 100% of the tax amount, so the IRS will usually take that and apply it as the tax itself, if the employer doesnu2019t correct it himself first. In that case, you no longer owe the tax, but you owe the employer the amount of the tax (without interest or additional penalty), because he paid your tax on your behalf.Hereu2019s where it gets complicated. Whether and how the employer gets the money back from you is a matter to be settled between the two of you u2022 the IRS has nothing to do with it and, frankly, couldnu2019t care less. And assuming that weu2019re not in the same calendar year (which we canu2019t be), the employer just withholding that amount from your pay may very well violate state laws (depending on your state, obviously, but most would require your consent). In the meantime, the employeru2019s payment of the employee-FICA that it paid was additional wages to you, and the withholding (income tax and FICA) on that has to be taken from your other paychecks (or else the problem would occur all over again).There is a way in which the employer can get away with very substantially reduced penalties, but that applies only in cases of unintentional misclassification (as an independent contractor), and thatu2019s not what happened to you. First, you were given a W-2, which indicates that you were treated as an employee. Second, you dont say anything about u201cforgettingu201d to withhold income tax u2022 and that in and of itself disqualifies the employer from taking advantage of these reduced penalties. (If they withheld income tax, they obviously were not mistakenly treating you as a contractor.)