I just looked it up [1] and depending upon filing status (single, married, head of household) the tax on the net taxable income of $50,000 (after deductions, expenses, etc) is between $6,576 and $8,278. $12,000 in taxes don't start until $65,000 net income.

[1] https://www.irs.gov/pub/irs-pdf/i1040gi.pdf

that's pretty much what I was thinking.