Q. I just got billed for failing to pay estimated taxes. Why wasn't this part of turbo tax?
Your question ("part of turbo tax") could mean one of two things:
1. you weren't given a chance to pay estimated 2023 taxes when you completed your 2022 tax return, last year or
2. You weren't given a chance to calculate you own penalty on form 2210, when you did your 2023 taxes.
Either way, the answer is the same: It was part of TurboTax, but it was optional. You chose not to do it.
In the 2nd case, it's usually better if your let the IRS do the calculation. The one exception is if you need to use the "annualized" method (when a large part of your income was received late in the year).