The Minnesota Dept of Rev website says deduct $35 from car registration fee to calculate allowable amount for deduction on fed tax form. Turbotax doesn't address. Why?

You'll record car registration fees on Federal Schedule A - which is outside of Minnesota-specific material that would be recorded/requested during the state return.

If Minnesota has specific guidelines for what to include on your federal return, you would ultimately refer to the guidance of your state's department of revenue. TurboTax provides you the space to enter a value - what that value is must be determined by you: http://www.revenue.state.mn.us/individuals/individ_income/Pages/Deducting_Vehicle_License_Fees.aspx

Turbo tax provided very specific instructions on calculating the value to enter. Incorrectly, since it doesn't consider your state requirements. As a result the amount claimed would be incorrect if an inexperienced tax filer just followed Turbo Tax guidance. I wonder what other topics are not calculated correctly depending on the filer personal information. Goodbye Turbo Tax, hello local tax professional.