Inexpensive, one-year health insurance policies could put government-subsidized Obamacare out of business, reports Fox News.

The plans, which are for sale outside of Obamacare exchanges, usually cost far less than similar Affordable Care Act policies. The health plans are gaining popularity as uninsured Americans learn they are required to obtain health coverage.

There are four catches, however:

1. The health insurance policies are only good for one year. Customers can always sign up for Obamacare if they don't renew the short-term coverage.

2. Customers will still have to pay the tax penalty for not having Obamacare insurance. That cost is $95 annually per person and could rise.

3. Pre-existing conditions are rejected.

4. If you develop a pre-existing condition while on the short-term plan, that insurer will provide care until the end of the term and then decline to continue coverage.

Providers have claimed a rapid growth in plan sales, which typically have a monthly premium of slightly over $100, compared to $271 for traditional plans.

"It's because the product is typically half the cost of ACA plans, and you can chose any doctor or hospital," Health Insurance Innovations CEO Mike Kosloske said.

If enough healthy and young people switch to the non-Obamacare plans, it could cause a serious problem for higher priced Obamacare plans.

"If the Obamacare health insurance exchanges are to function properly, it is crucial that a substantial number of people ages 18-34 join them," the National Center for Public Policy Research wrote in a study last year, according to Fox News. "This age group that is young and relatively healthy must purchase health insurance on the exchanges in order to 'cross-subsidize' people who are older and sicker. Without the young and healthy, the exchanges will enter a 'death spiral' where only the older and sicker participate and price of insurance premiums will increase precipitously."

Obamacare supporters say the program's taxpayer-funded subsidies will keep customers from leaving. 

"Basically, people making $37,000 or less should go on Obamacare. People with serious pre-existing conditions -- they should go on Obamacare. But for everyone else, including the penalties and including the subsidies [for Obamacare plans], we cost 30-50 percent less and have that freedom of choice with providers," Kosloske said.