If you are using the TurboTax online editions, to get Audit Defense you would need to purchase the optional Max Benefits
See this TurboTax support FAQ for how to get Max Benefits - https://ttlc.intuit.com/turbotax-support/en-us/help-article/intuit-product-orders/get-max/L9ZW1BYc5_...
If you are using the TurboTax desktop editions, the option to purchase Audit Defense will be in the File section of the program.
