Unfortunately, no. You can't add Audit Defense after filing your return. If you filed your tax return with TurboTax, you already have the TurboTax Audit Support Guarantee. TurboTax also offers Audit Defense, an optional add-on product that must be purchased when you file your taxes.
Please see the FAQ below for more information.
https://ttlc.intuit.com/replies/4204836
