The IRS uses the Schedule D tax computation method.

[FJS123]

What method does TurboTax Premier use to compute taxes that involve Capitol Gains, interest, and both Qualified and taxable dividends? thank you

[DoninGA]

TurboTax uses the IRS Qualified Dividends and Capital Gains Tax worksheet as required by the Internal Revenue Code of the United States - https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf#page=40

[rjs]

There are seven different methods that can be used to calculate the tax on Form 1040 line 11a of your 2018 tax return. TurboTax uses the method specified by the IRS instructions for Form 1040 line 11a on page 38 of the 2018 IRS instructions for Form 1040.

In TurboTax, the Tax Smart Worksheet shows which of the 7 methods TurboTax used for your return.

You can download the IRS instructions for Form 1040 from the following link on the IRS web site.

Instructions for Form 1040

In the IRS instructions, note that knowing that you have capital gains and qualified dividends is not enough to determine the correct method to use. You have to know the amounts on specific lines of Schedule D. Also, there could be other things in your tax return, that you haven't mentioned, that could require using a different method.

[Hal_Al]

It depends on all the details of your income.  For most people, TurboTax (TT) will use the Qualified Dividends and Capital Gains Work Sheet.  When needed, TT will automatically select the Schedule D worksheet, instead. The most common reason, for using the Sch D w/s is section 1250 gains.  See lines 16-20 on Schedule D