I am planning on purchasing the Deluxe desktop edition but if I run into an issue and need Premier can you upgrade through app or do you need to purchase the Premier edition for full price?
You can upgrade from Deluxe to Premier within the program if you need to---you just pay the difference between the price for Deluxe and Premier. BUT----do not say you will pay that fee by paying it from your federal refund, or it will get you for an extra $40 "refund processing fee" along with the upgrade fee. Pay for the upgrade upfront using a credit or debit card
Just a note that all of the TurboTax desktop editions include the same forms, schedules and worksheets.
You can upgrade at any time from your current Deluxe edition by clicking on Upgrade TurboTax at the bottom right of the desktop program screen. You would only be charged the difference in price.