Why do you think your taxable income should be zero? Here's what I get from the figures that you gave.
Unspecified income $27,224
Long-term capital gain 9,000
Short-term capital loss - 400
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Adjusted Gross Income $35,824
Standard deduction (MFJ) - 29,200
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Taxable Income $ 6,624
From the information you provided, your taxable income should be about $6,624. The question we might ask is why TurboTax calculated it as only $4,707. There may be some other facts that you have omitted.
Nevertheless, again based on the information you presented, your income tax should be zero, so it's not clear why you have to pay $1,500. Again, there may be some facts that you have omitted. You might owe some other taxes, even if you don't owe any income tax.
You didn't say what types of income are included in the $27,224. If some of it is self-employment you probably owe self-employment tax, even if you don't owe any income tax. Do you have a Form 1095-A for health insurance from the Marketplace ("Obamacare")? If so, you might have to repay some of the advance premium tax credit that you received during the year. These would appear as "other taxes" on Form 1040 line 23. The details of any other taxes would be on Schedule 2.
What line of Form 1040 is the $1,500 on? What are the exact amounts on Form 1040 lines 16, 23, 24, 33, and 37?
See the following FAQ for instructions to view your Form 1040 in TurboTax Online. "Preview my 1040" will also show you Schedules 1, 2, and 3.
How do I preview my TurboTax Online return before filing?
If you have further questions, please provide exact amounts and specific form and line numbers.
