Discrepancy between TurboTax directions, and form directions for IA 2210 (underpayment of estimated tax)

[Fahngieb]

TurboTax asks me to input information for determining my penalty for underpayment of estimated Iowa state taxes. It requests me to give a value for my 2017 Iowa tax liability, which will determine the value of line 5 of form 2018 IA 2210.

Turbotax directs me to compute this value by taking the value of line 55 of my 2017 Iowa return, and subtracting lines 63 through 67.

On the other hand, the directions of form 2018 IA 2210 (found here) direct me to compute this by taking the value of line 53 of my 2017 iowa tax return and subtracting lines 63 and 65.

These two alternatives result in different penalty amounts, and the turbotax directions result in a smaller penalty for me, since the value is reduced by my "extension" estimated tax payment for IA tax year 2017 made in april of 2018.

Which one is correct? are they both acceptable?

Thanks for any help that you can provide.

[Critter]

I would follow the program instructions to compute the estimated underpayment tax penalty  ... the state will compute a final penalty based on when you actually file and they receive the payment.  Expect the bill for late payment to come.