IRS website for the CP23 - https://www.irs.gov/individuals/understanding-your-cp23-notice
TurboTax has a 100% Accurate Calculation Guarantee that if the software made a mistake in a calculation then TurboTax will pay you back any penalties or interest because the the error. TurboTax does not pay any taxes owed.
See this TurboTax support FAQ for the Accurate Calculation Guarantee - https://ttlc.intuit.com/turbotax-support/en-us/help-article/account-management/turbotax-100-accurate...
