TT says max Roth contribution is $6500 for 2018. Did $24500 thru payroll deductions to Roth 401k.

I contributed $24500 in 2018 to Roth 401k thru payroll deductions.  On Roth IRA Contribution Limit Worksheet under Your IRA TT says max Roth contribution allowed is $6500.  Spouse is retired, no income.  TT wants to ding me 6% of the "excess" $18000 on 1040 line 14.

Seems like TT forgot the contributions were through payroll deductions, as entered from my W-2.  What now?