We received notice stating that we underpaid taxes by $189.94, notwithstanding that we solely use TurboTax for calculation of our taxes, and we paid both the quarterly estimated taxes and the amount due as calculated by TurboTax. We have attempted to check our account on the IRS website and got the message that it was" not available at this time". We are longtime users of TurboTax and have never had an error previously. TurboTax has a 100% accuracy guarantee. Will TurboTax/Intuit pay this amount due?
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-calculation-guarantee/L30iuaxMC_US_en_US?uid=lbh2orba
"...we paid both the quarterly estimated taxes and the amount due as calculated by TurboTax..."
A CP23 letter usually means that the estimated tax amounts you entered on your tax return did not match what the IRS had on file for your account.
https://www.irs.gov/individuals/understanding-your-cp23-notice
TurboTax guarantees that its calculations will be correct, but it can't guarantee that all user entries will be correct.