OK, I'll be honest I don't really understand what the Tentative Minimum Tax is but that was enough to make me ineligible for the EV charger install credit. Essentially, the EV purchase tax credit ($7500) plus the 2 child credits put me over the limit. So, basically there 8911 form establishes a maximum of tax credits that you can take in a given year before this one goes to zero. Thank you for the help on this. And agreed - a better TurboTax description of the reason it was zero would have saved me several hours of digging into this.
