ObamaCare is only affordable for a sweeping majority of those with plans because of taxpayer subsidies. However, more than half will have to payback those subsidies this tax season.

New research from the Kaiser Family Foundation, a health organization, finds that nearly all families which received tax credits to subsidize their Obamacare plans will either owe or be owed money when they file their taxes this year because of income or life changes after their OamaCare subsidies were calculated.

The government gave incorrect subsidies to a whopping 95 percent of ObamaCare households in the first year of operation. An estimated 50 percent of subsidy-eligible households were overpaid and will have to repay during tax season, while 45 percent were given smaller subsidies than they qualified and may get a money back. Overall, the estimated average repayment is $794 and the average refund is $773.

Like other programs that depend on estimated income based upon previous year’s income to calculate a benefit (such as student aid), customers who sign up for coverage report the previous year’s income and credits are advanced accordingly. Reconciling the estimated from the actual income reveals how accurate the subsidy amounts are.

For those whose income was higher than reported, they were over subsidized and will have to pay back some of or the entire amount overpaid when they file their taxes this year. Conversely, people whose subsidy was too low may get a refund.

In addition to income changes, life occurrences that change the size of a family also affect income subsidies such as a birth, death, or divorce. Clients are encouraged to report these changes to the Obamacare Marketplace, but not everyone remembers or is honest enough to do so.

To ensure that poor people on ObamaCare don’t lose too much of their returns, the government set caps on the repayment amounts of households with an annual income within the subsidy range (100-400% of poverty). Anyone above that level is out of luck and money this tax season.

The Hill reports:

Any owed or refunded dollars related to ObamaCare are just one piece of a person's overall tax filings. 

“The average refund is over $2,900, which would offset any repayment in most cases," a Treasury spokesperson said. "That is why Treasury estimates that the vast majority of marketplace consumers who benefitted from tax credits will still receive a tax refund.”

Some households will be paying back the majority of their tax credit. Middle-income households — with income from 300 to 400 percent of the poverty level — will repay about 65 percent of their tax credit.

Between 4.5 million and 7.5 million households received tax credits in 2014. This year’s tax season marks the first time that people will have to account for their ObamaCare subsidies or pay penalties for lacking coverage.

In ObamaCare’s first year, people buying insurance received subsidies in advance based on their tax returns from 2012, which was the most recent year available.

People with the middle-level incomes were more likely to owe money — and to owe more.

There are some limits for how much money an individual or family would have to repay if their tax credits were too large. For example, families making less than 300 percent of the poverty level will not pay back more than $1,500. Anyone with an income greater than 400 percent of the poverty level has no cap on repayment.

For those who were overpaid and are counting on their tax returns they won’t be too pleased. While the average repayments make up only a portion of a customer’s tax returns, the amount can climb steeply if income changes dramatically from one year to another. In an example, Kaiser notes that single 40-year-old living in Atlanta, GA with a starting income of $17,000 (148% of 2013 FPL) may have qualified for advance payments totaling $2,614 for 2014. If the enrollee’s annual 2014 income increased to $23,000, she ultimately would qualify for $1,824 in premium assistance. Assuming she did not notify the Marketplace of her income change, she would owe a repayment of $750 (because $2,614 minus $1,824 equals $790, which exceeds her repayment cap of $750). If her annual 2014 income rose even higher to $46,000, she would no longer be eligible for assistance and would be required to repay the entire $2,614 she received in advance payments.

ObamaCare in theory and application remains fraught with problems. The more we find out what was in this bill, the more we realize that it is unworkable.