The Refund Advance will be available this year to select customers. You will not be able to self-select into the offer. If the offer is available to you then you will be able to select it in the Your refund info step of the File section. Here's an article you can view for more information.
https://ttlc.intuit.com/replies/6467221
The Advance won’t come until after the irs Accepts your return.
https://ttlc.intuit.com/questions/4517864-about-receiving-your-refund-advance
