When I look at the IRS Tax Computation Worksheet it doesn't match what Turbo Tax figured for tax owed based on my taxable income. I even calculated the marginal tax rate by hand for each bracket and I come out to the exact same figure as the IRS.gov worksheet. TurboTax for some reason is coming up with tax I owe $888 lower. Usually when I double check all figures it's correct not sure why this year would be any different with TurboTax.
TurboTax uses the IRS tables to compute your tax liability.
You may see a difference between the tax calculation by TurboTax and your manual calculation when you have long-term capital gains and/or qualified dividends which are taxed at a lower rate.
Long term capital gains are taxed at 0% if your taxable income is less than $47,025 for Single or MFS or less than $94,050 for MFJ..
However, long term capital gains are included in your taxable income for the calculation of these thresholds, and that part of long term gains which crosses over $47,025 (Single or MFS) or $94,050 (MFJ) is taxed at 15%. For taxable incomes over $518,900 (Single); $291,850 (MFS) or $583,750 (MFJ). The long-term capital gain tax rate is 20%.
Qualified dividends are taxed at the same rates as long-term capital gains.
Please read this IRS document for more information.
Qualified Dividends (box 1b on any 1099-DIV forms) and LT Capital gains (Box 2a on 1099-DIV, and any LT security sales on 1099-B/8949) are taxed differently...starting a 0% and up-to- 15 or 20%.
Look for the Qual Dividends & Cap Gains tax worksheet....that's the most common tax calc form (though, occasionally one of several other tax calcs might be used)