The TurboTax accuracy guarantee essentially covers calculation errors such that Intuit will pay you penalty and interest if you have to pay an IRS or state penalty or interest because of the calculation error.
See https://ttlc.intuit.com/community/charges-and-fees/help/what-is-the-turbotax-100-accurate-calculatio...
Intuit will not, however, pay any amount of actual tax that was due.
