There is no Social Security deduction on a tax return. Do you mean that the IRS said the taxable amount of Social Security was wrong? Did the IRS change anything else on your tax return? The taxable amount of Social Security depends on your other income. If the IRS changed something that increased your other income, that would increase the taxable amount of Social Security. The Social Security calculation was correct for the amount of income that you reported on the tax return that you filed. When the IRS says it was wrong, they mean it was wrong for the new amount of your income after they changed your income.
