My Taxable Income is $1634, why is my Tax Liability $1643? I'm self employed so using the 15.3% for self employed shouldn't I owe $251.38 if my Taxable Income is $1634?

My total income is $14982, deductions is $13348, Taxable income is $1634, Blended tax rate is 100.6%, and Tax liability is $1643. I'm confused where the $1643 came from