Under the Charging Station credit, Turbotax is noting $0 for the personal portion of the Alternative Vehicle Refueling Credit. If I lower the Energy Efficient Vehicle Credit amount below $7500 the Charging Station Credit then shows up in my deductions. If there is a shared cap to both credits my Vehicle Credit is only $3750 but Turbotax seems to require listing $7500 in my deductions to get the result of $3750.
The only cap on the credits is the amount of your tax liability. Other tax credits will reduce the amount available for the Charging Station Credit. Total credits cannot exceed your tax before credits.
Be sure that you do not change the maximum credit amount shown on the screen, otherwise the calculation will not be correct.
TurboTax will calculate your maximum credit based on the details entered for your vehicle and any applicable phase-out based on the purchase date.
On the screen where it shows the amount of credit you qualify to receive, the box at the bottom of the page is showing the maximum credit that would have been allowed for your vehicle had a phase-out not applied. Your credit may be limited by the phase-out. If you change the number on that screen, your credit will not be calculated correctly.
The information on the screen says this field is for adjusting the amount of maximum credit it is does not match the manufacturer's specification. The number entered here will be the maximum credit that you may receive prior to any limitation being applied. If you change it, your credit will be based on the number entered.