As for your question about TurboTax tax calculation differing from the IRS Tax Tables, be aware that there are several situations in which TurboTax does not use the tax tables for the complete calculation. For instance, did you have any qualified dividends from investments? Or did you have capital gains from stock/bond/mutual fund/other property sales or capital gains distributions? If so, the tax calculation in those circumstances is performed on the Qualified Dividends and Capital Gain Tax Worksheet. That's the most common cause for TurboTax calculating a tax amount less than the IRS Tax Tables. Qualified dividends and capital gains are taxed at a lower tax rate than the tax tables alone, i.e., as low as 0%, 15%, or 20% depending on income.
There are also some less common situations that require alternate calculation. But first check to see if you had any capital gains or qualified dividends that explain what you are experiencing. If so, and if you have a full copy of the return that includes the worksheets, look at the Qualified Dividends and Capital Gain Tax Worksheet for the tax calculation.
