Letting the other parent claim the child tax credit would have no affect on your refund. You would just be trading the $2000 of child tax credit for another $2000 of EV credit. A $2000 reduction in 401K would increase your taxes by $440 thus increasing your EV credit by $440. This also would have absolutely no affect on your refund and you would lose the benefit of $2000 of tax deferred investment and maybe company match if they match your contribution.
