I finally discovered what happened. The IRS sent an adjusted refund notice. The estimated tax on line 26 of 1040-SR was incorrect. When I went back and looked at the 4 estimated payments, they were correct, but Turbo Tax added an additional payment when it put the information on line 26. I am not sure at this point, how I could have changed this since I assumed that Turbo Tax could handle a simple calculation. Please let me know how to go "under the covers" to change this kind of thing if it happens again. By the way, my state tax was also overstated by one payment as well.
