The tax credit is actually a credit on your taxes, not your income. If your income tax on whatever income is say $5,000, the amount you will owe is $500. A $4,500 savings. An accountant who doesn't know the difference between a tax credit and a deduction is should be canned. "You're fired!"
Some tax credits are "refundable", meaning if your tax paid is zero, the government will send you a check in the amount of the credit. This is not a refundable credit, so your income taxes have to be over $4,500 to take full advantage.
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