If you entered everything into TurboTax correctly and TurboTax did not produce any Form 2210, it's likely that the IRS letter is incorrect. Make sure that you entered the correct amount of your previous-year's tax liability. If you omitted that causing TurboTax to assume incorrectly that your previous-year's tax liability was zero, TurboTax would not have produced the required Form 2210.
This is my thought but it leaves me unable to get a 2210 from TurboTax which seems like an oversight - I should be able to produce one to dispute this IRS charge.
I use TurboTax every year so it already has my previous year tax liability. I did not need to enter that myself.
