It appears that the tax calculations in the software are wrong. I added $13 of income and my tax liability went up by $12! When will Intuit fix the tax tables?

Thanks VolvoGIrl but that is not the problem. First of all, going into a “higher tax bracket” just affects the additional income, not the income which was in a lower bracket. A common misunderstanding. Whether this additional money was in the 22% or 24% bracket would not generate an increase of $12 in tax on $13 of income.

Second, I understand that a change in income can result in a loss of deduction or credits. That did not happen here. I added $13 of income, my taxable income went up by $13. My tax went up by $12.

Bottom line - TurboTax has a programming error. Their tax calculation without the $13 was a few dollars too low,. Their tax calculation with the $13 was a few dollars too high. Those two error compounded to result in the $13 having a 92% marginal tax rate.

The program can’t seem to do simple math.

There are like 7 different ways to calculate the tax.
It depends what kind of income you have. Even though the full amount shows up in the total income on the 1040 line 7, if you have capital gains or qualified dividends the tax is not taken from the tax table but is calculated separately from Schedule D. The tax will be calculated on the Qualified Dividends and Capital Gain Tax Worksheet. It does not get filed with your return. In the online version you need to save your return as a pdf file and include all the worksheets to see it.

Plus if you have self employment income you owe Self Employment tax on it in addition to regular income tax.