EV credit is a non refundable credit meaning it is limited by the amount of unused tax that it can offset. I said unused because the child tax credit is a higher priority credit and will be deducted from the tax before the EV credit is deducted.
The taxable income on $62,728 minus $18,000 standard deduction for head of household filing status would be $44,728 in 2018. The tax from the tax table would be $5,095.The child tax credit increases to $2000 for 2018 leaving $3,095 for the EV credit to offset. So you would get $3,095 of EV credit reducing your tax to $0. You would get back as a refund all of your tax withholding from throughout the year.
