Total taxable income multiplied by effective tax rate should equal taxable income. It is a simple formula, why are your numbers so far off?

[MarkH2]

The effective tax rate is not as straight a formula as you stated. If you added the taxes that you pay on each portion of your income, and then divide it by your total income (then multiply by 100), you would get your "effective tax rate". This is the actual rate you pay on your taxes, regardless of your marginal tax rate.

If your marginal tax rate is, for example, 25%, that doesn't mean that ALL of your income is taxed at 25%. Income is actually taxed at different rates. Here's how it works:

Say that your income for 2016 is $40,000 and your filing status is Single. Your first $9,275 will be taxed at 10%. Every dollar from $9,275 to $37,650 will be taxed at 15%. And every dollar from $37,650 to $40,000 will be taxed at 25%.