Two New Taxes on Net Investment Income and Medicare Will Take Effect on January First At the Wall Street Journal's Tax Report, Laura Saunders explains.   The word is out: Two new taxes on the affluent and wealthy will take effect as scheduled next year as a result of the Supreme Court's decision upholding the health-care overhaul. One is a new 3.8% tax on net investment income, and the other is a 0.9% incre ...