Not every Obamacare subsidy recipient will owe money back when they file their tax returns this season. An estimated 45 percent will receive subsidy money because their actual income ended up being lower than what they had estimated when they applied for insurance. About 5 percent will neither owe back any part of their subsidy nor get more money in the way of a subsidy for last year.
But about 50 percent of subsidized Obamacare customers will owe money back, which will offset their tax refunds or wipe them out altogether, according to a recent Kaiser Family Foundation report.
The US Treasury Department estimates that most Obamacare customers will still get an income-tax refund, meaning they won't have to cut a check to the IRS for repaid subsidies. A Treasury spokesman said average refund is about $2,900, which would offset any repayment in most cases.
Still, repaying the subsidies could leave people with lower refunds than they were hoping for, or worse. The average subsidy repayments range from $667 from low-earning subsidy recipients to $1,380 among people who earn between 300 and 400 percent of the poverty level.
But, "If you are below 400 percent of poverty, there are limits on what you have to pay back," said Bradley Heim, an associate professor at Indiana University's School of Public and Environmental Affairs, and former economist in the U.S. Treasury's Office of Tax Analysis.
For a lot of people, this will only be a trivial amount, Heim said. But the "absolutely worst-case scenario" is someone in Highsmith's position, who ends up earning more than 400 percent of the poverty level after receiving subsidies during the year.
While the number of people likely to go over that "cliff" last year is tiny compared to the 6.7 million Obamacare customers, Heim noted that people who go over the 400 percent poverty threshold by even a dollar can end up owing several thousands of dollars back in subsidies.
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"All those subsidies go to zero once you hit 400 percent of poverty," Heim said.
"You can go from a $10,000 [subsidy] to be eligible for nothing."
Jamie Long, who prepared Highsmith's taxes, said he was the one of three people who visited her office who owed back subsidies this season.
"The lower [amount] was about $550, and the middle was around like $3,800" in repayments, Long said.
All of those people reacted with "genuine surprise" when they were told they owed a repayment, she said. "They weren't aware that was something that could happen, that they could receive so much in the subsidy and have to pay it back."