I checked the block with the filing date to figure the amount I owe and it populates. Then under review it changes and asks me to check the box for IRS to calculate and send me a bill (or wait until early Feb for an update). Why is the software doing this? What type of update are we waiting for? Software or IRS? The result is additional interest as days go by. Should I trust the IRS calculation will be the same as what the software presents?
I'm not sure why the software is doing what you describe. Early in the tax season TurboTax updates the software based on changes from the tax authorities as well as de-bugging of the TurboTax software, as is the case with all software products.
The IRS will do a calculation to determine what your penalty is whether TurboTax calculates it or not. If the IRS does not agree with TurboTax's calculation, they will adjust your tax accordingly. So, if you file your tax return now, your ultimate penalty should be the same as it will be if you wait for the TurboTax update, accept for the cost involved with waiting.