1) Going forward, is there a way to prevent this (other than to find more deductions or credits, or to overpay more in estimated payments)?
What I mean is, does TurboTax Desktop have a tool to check for how much interest I owe (similarly to the Estimated Payment penalty check tool), so that I can add this interest amount to my total payment amount at the time of filing the return, instead of waiting for the CP 14 notice?
No. Turbotax does not compute interest on late payments. 100% of your tax is due 4/15 (or the next business day should 4/15 fall on a weekend or holiday) of the following year except in certain situations like disasters.
2) Does TurboTax cover such a scenario in its money-back guarantee, which says that I won’t end up paying more than its calculated balance due (assuming that the data inputted was correct and complete)?
Interest on a late payment not due to a calculation error made by Turbotax is not covered
