You're right. I confused AGI (line 37 on the 1040) with taxable income (line 43). And of course even that doesn't account for a variety of credits including EIT

You're right. I confused AGI (line 37 on the 1040) with taxable income (line 43). And of course even that doesn't account for a variety of credits including EITC. But everyone should have some idea what their taxable income is, and what credits they're eligible for. If the former is X and the latter is Y, you can take Chart(X) - Y and it will be fairly accurate for you.