Depending on how you look at it, some income was charged at way more than 100% in this case. The EIC has a strict limit on investment income. If you're under the limit by $1, you can claim the full amount of the credit. If you're over by $1, you get no credit. Most of these dividends didn't affect their taxes by much at all, but there was that $1 that bumped them over the limit, eliminating $3,000 in credits. You could easily argue that particular dollar was taxed at something like 300,000%.