What is the difference between TurboTax Deluxe offered on official app, versus TurboTax Deluxe online Edition offered by Costco website?

 

Getting started

There is no difference between the mobile app and TurboTax Online, The iPhone/Android app is TurboTax Online, but formatted so that it's easier to use on a phone or tablet.

 

Normally, when you use TurboTax Online, you would pay per return. The Deluxe package they sell at Costco allows you to file 8 deluxe returns at a discounted price. If one (or more) of your 8 returns needs to be upgraded, then for that return you would be credited the price of 1 Deluxe return, and you would only have to pay the difference.