Net Investment Income Tax (NIIT)
The Net Investment Income Tax is a 3.8% tax to certain net investment income of individuals (also trusts and estates) that have income above threshold amounts. It applies to tax returns 2013 or later. Married filing jointly tax returns with modified adjusted gross incomes of over $250,000 are subject to the NIIT, as are married filing separately at $125,000, singles and heads of households at $200,000, and qualifying widow(er)s at $250,000.