There are seven different methods that can be used to calculate your tax, depending on what is in your tax return. The seven methods of calculating the tax are the Tax Table, Tax Computation Worksheet, Form 8615, Schedule D Tax Worksheet, Qualified Dividends and Capital Gain Tax Worksheet, Schedule J, and Foreign Earned Income Tax Worksheet.
In the IRS instructions for Form 1040, look at the instructions for line 16. Starting at the bottom of the right column on page 32 it explains the seven methods that can be used to calculate the tax on line 16.
In TurboTax the Tax Smart Worksheet has 7 checkboxes that show you which method TurboTax used. I don't know if there's any way to see the Tax Smart Worksheet in TurboTax Online. It is part of the "Form 1040 or Form 1040-SR Worksheet," which may not be included in the PDF of your return. If the Print Center allows you to select a specific form, printing the Form 1040 or Form 1040-SR Worksheet should include the Tax Smart Worksheet, after the form itself. In the CD/Download TurboTax software you can see the Tax Smart Worksheet in forms mode, between lines 15 and 16 of the Form 1040 or Form 1040-SR Worksheet, and you can print a specific form.
