It is worthrestating thatthisresultdoes notapply in allcases, and that additionalthreadsmaygivea highermessageratethanextraexecutiongroupsforotherworkloads.
The issue is that a great number of small businesses are taxed as pass- through entities, so the rate of the corporate tax would not necessarily apply to those taxed at the individual rate.
Third, the United States is one of the few remaining countries (PDF) that has a "worldwide" tax system, meaning that we apply the 35% top rate to the worldwide profits of U.S-based companies: that is, on the profits made by foreign subsidiaries as well.