How is the "tax you're supposed to pay" calculated?

[SJ80]

I have a total income of $88,422, minus the $24,000 standard deduction, minus $164 Qualified business income deduction.  This means I have a taxable income of $64,196.  When I look this up in the 2018 1040 Tax Table, it says my tax is $7,320.  TurboTax is telling me my tax is $7,444, using all the same inputs as above.  Why the difference?

[DanaB · Accepted solution]

The difference might be the self-employment tax you have to pay. You will have the tax shown on your taxable income on Form 1040 line 11. If you had Qualified Dividends and Capital Gains then you cannot use only the taxable you will need the Qualified Dividends and Capital Gain Tax Worksheet to calculate the tax on line 11. The Self-employment tax will be included in line 14 and is carried over from Schedule 4.

[SJ80]

Thank you!  The difference was in the 1040 Line 14.