Using Turbotax Premium online version, there appears to be an error regarding an underpayment of state withholding penalty which I believe to be incorrect: My state tax for 2016 was $2335. During 2017 I made 4 payments of $590 each totaling $2360. And yet, Turbotax indicates I need to pay a $198 penalty. Ive had accountants look at this, and they concur no penalty. Isnt the law that so long as you pay at least 100% of the prior year's tax liability in estimated taxes, there is no penalty regardless of how much more you earned in the current year?