You can still deduct vehicle expenses using either amount. But, if you use the ''net'' figure, do not deduct the expenses that are included in the ''Expenses, fees, and taxes'' section on the Uber Summary since you will have already deducted them by using the ''net'' amount. If you use ''gross'' earnings, you can deduct the ''Expenses taxes and fees'' on your tax return & vehicle mileage.
For the 'expenses/taxes/fees' on your Uber Summary, using the net amount allows TT users to be able to use the Deluxe or Premier versions of the program (business deductions are not supported). If you want to deduct any business deductions on your return (fees, or taxes, or mileage), you have to upgrade to Self-Employed or Home and Biz. I hope I am clarifying and not confusing;)
