That is an additional "Net Investment Tax" assessed on certain forms of investment income received by high income individuals.....so it is subject to both normal taxes, plus an additional tax bump calculated on the form 8960.
https://www.irs.gov/newsroom/questions-and-answers-on-the-net-investment-income-tax
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
