Since every state is different, I don't know what is in the DC software, however the TurboTax guarantee is limited to any penalty (not the tax) that the IRS (or state) charges you for under paying your tax due to a TurboTax calculations error.
To discuss this with a TurboTax representative contact customer support - this is a user-to-user forum of other TurboTax users, not customer support.
There is no single published number because it changes contently depending on the nature of the call and agent availability. Following the link below will either give a current number for you to call or take your number for a callback.
(Note that phone support is for paying customers only. There is no phone support for Free Customers.)
Here is a TurboTax FAQ for contacting customer support.
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
