Can you figure it out?  Like did you enter one payment twice?  Is it the amount of your 2017 refund?  Since you seem to have the Desktop program open it up and look around.  Maybe you typed one amount wrong.  But first save or duplicate your return with another name do you don't mess it up. 

What were your 4 payments and what showed up on line 66?

You can switch to Forms Mode and look around at the payment worksheet.  You should be able to figure out what happened.

Hello,

OK thank you - I looked at the form - the only thing I can determine may have happened is that the prompt mentioned 2017 and that I added the 2017 amount to the payments I made in 2018. Just doublechecking - does Turbotax do any calculation on Schedule 5 or is it only a number input by the user?

Thanks!

Lori

Well it adds up the individual estimated payments you entered on each date.  Did you enter or say you applied your 2017 refund?  It may have asked you if you got a refund last year.  Is the difference your 2017 refund?

 Or you think you entered a 2017 estimate payment?  Like maybe you paid the 2017 4th quarter estimated payment in Jan 2018?  You weren't suppose to enter that.