You're not calculating it right. 40,000 - 6300 for the standard deduction - 4050 for an exemption = ~29,000. First ~9000 is taxed at 10%, next ~20,000 for this

You're not calculating it right. 40,000 - 6300 for the standard deduction - 4050 for an exemption = ~29,000. First ~9000 is taxed at 10%, next ~20,000 for this person is taxed at 15%. Total income tax that could be reduced by the $7500 rebate for this person would be ~$4000 worst case.