The IRS refers to as a "calculation error" any disagreement between your tax return and the calculations that they do based on information returns sent to the IRS directly from payers. Because of this, a "calculation error" indicated by the IRS rarely indicates a problem with TurboTax and most often means that the user of TurboTax either omitted some item of income or entered some item of income or a deduction or credit incorrectly.
As the others have said, if you describe the nature of the error identified by the IRS, it's likely that it will become apparent how the error occurred.
