The Patient Protection and Affordable Care Act, better known as Obamacare, has a number of complex provisions. But one way in which subsidies help reimburse some people for out-of-pocket costs has a trap for the unwary that can cost you valuable subsidies if you're not paying attention.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, looks at cost-sharing provisions under Obamacare. Dan explains that for those earning less than 250% of the federal poverty limit, subsidies can pay some of the cost of copayments, deductibles, and other out-of-pocket costs under Obamacare insurance policies. But as Dan points out, you have to choose a silver plan or above to qualify for cost-sharing subsidies. Dan concludes with comments about how greater knowledge of the cost-sharing subsidy provisions could help WellPoint (ELV 1.11%) and other insurance companies get more customers on more lucrative plans.