If President Trump decides to cut off payments to insurance companies called for under the Affordable Care Act, it's going to cost him.

Or, more accurately, it's going to cost taxpayers — about $194 billion over 10 years.

The cost is "eye-poppingly large," says Nicholas Bagley, a professor of health law at the University of Michigan. "This single policy could effectively end up costing 20 percent of the entire bill of the ACA."

The deficit figure comes from the Congressional Budget Office, which on Tuesday released an estimate of the budget impact of ending what is known as cost-sharing reduction payments. Those are payments the federal government makes to insurance companies to reimburse them for the discounts on copays and deductibles that they're required by law to give to low-income customers.

The reports also says premiums for benchmark plans sold on the Affordable Care Act exchanges will rise about 20 percent next year and about 25 percent by 2020. The cost to consumers, however, would stay the same or even decline, because the premium increases would be offset by tax credits, which we explain further below.

Trump threatened repeatedly to cut off the payments, which he has called "bailouts," during the unsuccessful effort by Senate Republicans to repeal and replace the Affordable Care Act, also known as Obamacare.

More recently, the president has remained mute on the topic, and insurers have been left to wonder whether they will receive a check this month for the discounts they paid out in July.

Bagley says there is no good policy reason to cut off the payments. "If you can cover roughly the same number of people for about $200 billion less, why wouldn't you want to do that?" he asks.

Cutting the cost-sharing payments ends up costing the government more because insurance companies say they will raise rates in response. Under the Affordable Care Act, people with lower incomes who buy insurance on the exchanges get a tax credit, so their costs remain stable as a share of their income. That means that when premiums rise, those government subsidies rise as well.

The CBO says for people with incomes below 200 percent of the federal poverty level, the out-of-pocket cost of insurance would remain about the same because of the bigger tax credits. For those with incomes between 200 percent and 400 percent of the federal poverty level, the cost to buy insurance could actually get cheaper.

Last year, about 85 percent of people who bought Obamacare insurance got a tax credit, according to the Centers for Medicare and Medicaid Services.

"The CBO analysis makes clear that ending cost-sharing subsidies would be a perfect example of cutting off your nose to spite your face," says Larry Levitt, a vice president at the Kaiser Family Foundation. "Premiums would rise, and the government would end up spending more in the end through tax credits that help people pay their premiums."

The CBO report confirms earlier analyses, including this one by Kaiser and this one from the consulting firm Oliver Wyman, that suggested eliminating the cost-sharing payments could make policies cheaper for some individuals.

Some insurers may decide to leave the ACA markets altogether if the subsidies were to disappear "because of the substantial uncertainty about the effects of the policy on average health care costs," the CBO says. The agency estimates about 5 percent of the population would not have access to insurance through the ACA markets next year if Trump ends the payments.

But the agency says insurers would come back over the next two years.

Timothy Jost, a professor emeritus of health care law at Washington and Lee University School of Law, says that picture may be a bit too rosy.

He says the CBO assumes that state insurance commissioners will allow insurance companies to set premiums in ways that would be most advantageous to them, thereby ensuring they continue to sell policies on the Obamacare exchanges. But that may not happen, Jost warns.

"CBO assumes that things will work out rationally, and there will be a smooth landing," he says. "It could be much more chaotic than that."

Last Friday, the Department of Health and Human Services extended the deadline for insurance companies to decide which health plans to offer on the Obamacare exchanges and what to charge.

The cost-sharing payments have been at the center of a political battle over the Affordable Care Act since before Trump took office.

House Republicans opposed to the health law sued then-President Barack Obama, saying the payments were illegal because Congress hadn't appropriated money for them. A judge agreed but allowed the administration to continue making the payments during an appeal.

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