Why do I owe tax money?

So from my understanding I made a grand less than in 2018, and I also paid my taxes via my checks. I have never had dependents, I'm was a full time student and I paid for more than half my expenses from August to December.
According to TurboTax I made ~12,400, the lowest since I turned 16 which was 4 years ago. Yet somehow TurboTax is also saying I made over 40 grand (which I couldn't have).
Is there a reason for this or should I contact the IRS?
Why do I owe tax money?
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