Almost a third of working Americans currently have some kind of medical debt and about 28% of those who have an outstanding balance owe $10,000 or more on their bills.

When asked if they've ever defaulted on those bills, about 54% of people with medical debt said they had, according to a new survey fielded by Salary Finance of over 2,700 U.S. adults working at companies with over 500 employees.

And that's among people who are employed and typically have health insurance, Dan Macklin, Salary Finance's U.S. CEO and co-founder of SoFi, tells CNBC Make It.

"Even if people have insurance, their deductibles are going up and people are spending more on health care," he says. "Across the country, across different income levels, we see the reason people are short on money and often need to borrow money is often related to medical debt."

Americans spend an average of about $5,000 a year on out-of-pocket health care costs, including insurance, prescriptions and medical supplies, according to the latest consumer spending data from the Bureau of Labor Statistics. That's double the amount Americans spent in 1984, according to an analysis of the Bureau of Labor Statistics's Consumer Expenditures Survey by data company Clever.

Last year, the cost of medical care rose 4.6% from what consumers were paying in 2018, the largest year-over-year increase since 2007, according to the Bureau of Labor Statistics's Consumer Price Index. Prescription drug prices and the cost of hospital services both rose 3% from 2018 to 2019, while physician services also saw a slight year-over-year increase.

It's not surprising, then, that 45% of survey respondents say they feel worried or stressed when thinking about health care costs. A third report they have avoided going to the doctor and getting medical care due to the cost.

Americans are depleting their own savings to pay their medical bills, Macklin says. In many cases, even if they and their immediate family have health insurance, Macklin says they may be helping other family members, particularly adult children, pay off medical debt.

Keep in mind this is occurring at a time when the U.S. workforce is solid and the economy has been on an upward trajectory. "It's great, in one sense, that unemployment is staying low and it's great that job growth continues, but those macro trends are masking the underlying pain people are feeling," Macklin says.

"Your salary may be going up, but when health care, education and housing costs are going up at a faster rate and they take up a large portion of your paycheck, then you're not necessarily richer off," he says. In fact, you're probably left with less, and that becomes a problem when big bills hit.

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