Prior to the passage of Obamacare, taxpayers were not required to pay Medicare tax on investment income. The recent passage of the Affordable Care Act has changed all that. As of January 1, 2013 taxpayer are required to pay a 3.8% tax on investment income if modified adjusted gross income exceeds $250,000 for married taxpayers filing joint returns and $125,000 for married taxpayers filing separately.If a taxpayer is single the amount is $200,000.

Interest and dividend income in addition to gain from the disposition of property is subject to this additional tax.