You probably didn't use the correct method for calculating the tax. There are seven different methods that can be used to calculate the
tax on Form 1040 line 11a, depending on what types of income you have
and other things in your tax return. The IRS instructions for Form 1040
line 11a, starting in the middle column on page 38, explain the
conditions for using each of the 7 methods.
The Tax Smart
Worksheet in TurboTax has 7 checkboxes that show you which method TurboTax used. Since you are using the CD/download TurboTax software, you can see the Tax Smart Worksheet in forms mode. It's between lines 10 and 11 of the Form 1040 Worksheet.
