@brantly
Wow. I am impressed with your knowledge on this. Thanks so much for the detail. It is a great help to both me and I am sure it will provide understanding to other readers in the future who are looking for the same information. It is great that you were able to use the correct terminology as I get confused reading posts and articles who might refer to the same thing in different ways. Your specificity really helps elucidate the concepts behind the calculation. This is very helpful for those who need to plan for their tax bills or make quarterly payments. So much better than just the plug and chug involved in Turbo Tax which does not result in meaningful understanding of more complex situations.
Thanks again!! 