I have to pay back my ObamaCare subsidy

Like Riddle, many Americans on the exchange will likely have to pay back some or all of their subsidies. Between 4.5 million and 7.5 million taxpayers received subsidies for insurance premiums when they signed up for coverage on Obamacare exchanges, federal officials said. These folks had to forecast their 2014 income when they applied. Those who underestimated their earnings either will receive smaller tax refunds or will owe the IRS money.
Some enrollees, however, had a change in circumstances — such as a raise, new job, marriage or baby — during the year that could affect their subsidy level. Obamacare enrollees were supposed to contact their exchange so it could revise their premium. Some people, however, did not know they had to notify the exchange or simply didn’t bother.
Also, just because someone qualified for a certain subsidy at the beginning of the year doesn’t mean they are ultimately entitled to it. It’s the total annual income that matters, so if an enrollee got a big raise mid-year, his entire subsidy may have to be repaid.