How do I know if I have maximum refund guarantee

it says that on the web site.

You don't, it's a fraud.

Intuit, your Maximum Refund Guarantee is a fraud. https://turbotax.intuit.com/corp/license/desktop.jsp section 5 requires customers fill out a Claim Request Summary but the link to the form is not a link, just underlined text. Fix the link or I'm reporting you to the NJ Attorney General.