he Affordable Care Act actually includes two surtaxes. One is a 0.9% additional tax that is applied to earned income; the other is a 3.8% additional tax on investment income. Each is computed separately.
Let’s take the 0.9% surtax on earnings. This kicks in when your income from a job exceeds a certain amount. If you are single, the threshold is $200,000 and $250,000 for married taxpayers who file a joint return. (You don’t have to be a mathematical genius to notice the “marriage penalty” inherent in this.)
Wages have been subject to a 2.9% Medicare tax for years: The amount is split, with the employee and employer each paying half, or 1.45%. (1) Starting with your first paycheck in 2013, if your annual salary exceeds the threshold, you will pay 2.35% toward Medicare. There is no increase in the amount employers have to pay.