what line is the $24k on?  these board would be "blowing up" if there was a bug.

what about 1099-C income where there is a 15.3% tax, or penalties from 1099R forms?

look on schedule 2

do you have any penalties for 1099-R withdrawals? (under 59.5 years old?)

do you have any 1099-C forms as you have to pay the 15.3% self employment tax related to social security. 

24,000 sounds like the Standard Deduction for Joint.  Actually the Standard Deduction is 24,400.   But if you took a early distribution from a 401K or IRA you may have the 10% early withdrawal penalty added.  But if your tax is way off go back and check all your entries, especially income on W2 box 1 wages.  You may have typed a decimal point in the wrong place or left it out.