Why my qualified dividends tax rate is 24.3% when IRS document says max is 20%?

Qualified dividends are taxed at the long-term capital gain rate, up to 20% depending on your tax bracket. The average rate could be higher because the added dividends push more of your other income taxed at your marginal rate. I can not imagine what can cause the ordinary dividends to be taxed more than the maximum rate.

see if there is form 8960 in your return. there is an additional 3.8% tax on net investment income tax that exceeds the threshold.