I got a IRS Notice CP71A saying I owe $11,280.01 from tax year 2018. I used TurboTax and pay for Audit defense. How do I get help responding to this?

TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-audit/turbotax-audit-support/L6AcMoNFD_US_en_US?uid=m5z7by9u