Wyatt, you haven't had to deal with this.  Katie probably thought she was fully subidized, then earned more income and had to pay back the subsidy.  One of my young relatives had the same problem, and had his refund reduced by $800 for JUST 2 Months  of Obamacare.  Prior to this law he could have bought try catastrophic insurance for less than half what Obamacare cost because he is healthy and young.  He should have just paid the penalty - he did the right thing and it cost him $800