Deductions & credits
You may be treating your total tax as your income tax liability, which it may not be. You may have self-employment taxes for instance included in with your total tax, but the energy credit does not apply to that. You can look at line 18 on your Form 1040 to see what your income tax was. Also, you would need to subtract from that certain credits you may have had (child tax credit, earned income credit, education credits, etc...) to determine your net income tax on which the energy credit would apply.
