Form 8615 - Kiddie Tax

[Yardley CPA]

In calculating the tax for children who have unearned income, must both line 15 and line 17 be filled out?  It asks for the tax on the child's filing status.  But also gives the option of the Qualified Dividends and Captial Gain Tax Worksheet?

I'm including a screenshot of form 8615's tax computation, along with the schedules ATX jumps to for 8615's Line 15 and Line 17.   The Qualified Dividends and Capital Gain Tax worksheet calculate zero tax for both.  The tax table for Line 15 is $146 and for Line 17t it's $318.  Can I use the Qualified Dividend and Capital Gain tax of zero for both lines? 

Tax Computation Section:

 

Tax Computation for 8615 Line 15:

Tax Computation for 8615 Line 17:

[Abby Normal]

Yes, but how is line 13 negative?