This is the e-mail I received...
"We’ve partnered with TurboTax to offer a $15 discount on TurboTax Premier federal products. When you visit TurboTax through Robinhood, you can get a $15 discount on tax filing services."
For information on how to receive an affiliate partner discount, please visit the help article below. If you need further assistance, please Contact Customer Support.
How do I get my TurboTax affiliate partner discount? - Intuit
TT issues various promotions and discounts throughout the season for their products. Usually these have a start date and an ending date. If you file and pay before the start or end of the promotion, you can not get the discount. They are not retroactive.