If the $12,500 was not reduced for your share of the Social Security and Medicare taxes taken out on that portion then the Company will not issue a corrected w-2 The taxable wage portion is not reduced if the repayment is in a subsequent year. Therefore, the W-2 is correct for 2020 and 2022. (2022 since they paid your salary rather than deducting the 412500 from it)
The claim of right credit (IRC 1341) will take care of the federal income tax. Don't know if you paid state income taxes. If you did since I don't know the tax laws of all the states, you will need to do some research to see how to get back the state taxes you paid on the $12,500. To get a refund of Social Security and Medicare taxes, you will need to file Form 843 with the IRS. This is separate from your 1040 and is not done by Turbotax. You will likely need a letter from the company confirming that they will not be issuing a refund of your Social Security or Medicare taxes.
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in the year of repayment, 2022, you can either
1) take as a deduction on Schedule A line 16 and denote it as IRC 1341 repayment OR
2) recompute the taxes in the year you received the bonus by reducing the taxable wages, box 1, of the w-2 by $12,500. The decrease in taxes is taken as a credit on Schedule 3 line 13d. There are no specific documents you need to attach for this but do keep your computation workpapers (like an amended 1040 for 2020) should the IRS inquire