that is correct - the refund has nothing to do with it - it's about the liability.
change you assumptions so there is no tax withholding during the year..... that doesn't change your liability but it does change how much a refund you are due.
The tax table amount would still be $7,000 in your example.. the EV rebate is the lower of this number or $7500. In otherwords, the liability can't go negative.
