I'm running some what if scenarios and find that at $10,000 for box 1a and 2a and 2b checked with box 7 marked 7 and IRA/SEP checked, I would owe zero tax. HOWEVER, if I bump that to $12,000, the tax owed skyrockets to $9,977. How is that possible if tax rate is 12% for under $75k agi??
