States and insurance companies scrambled to raise premiums for insurance plans sold on the Affordable Care Act exchanges Monday, after the White House announced it was ending key federal subsidy payments.

The subsidies, called cost-sharing reductions — or CSRs — are federal payments to insurers that are used to offset deductibles and other out-of-pocket health costs for lower-income Americans.

The White House announced it was ending the payments late last week. But insurers are still obligated to sell the plans, so companies would now like to make up the difference by raising premiums — and the quickly approaching open enrollment period beginning in November added urgency to the situation.

In many states, insurance companies had already priced in a possible end of CSRs to their rate requests, anticipating President Donald Trump’s move. In others, however, regulators explicitly asked companies to assume that the payments would be made — or gave little direction, leaving some insurance companies pushing for higher rates at the last minute.

In Montana, regulators had left it to insurance companies to make their own assumptions about next year. Two of the three insurers on its exchange had assumed the payments would be made and filed for relatively low, single-digit percentage average rate increases for next year.

On Monday morning, the Centers for Medicare and Medicaid Services gave notice to the state of Montana that health insurers could refile their rates to adjust for the loss of the subsidies.

Montana Health Co-Op, which had filed for an average 4 percent increase on its plans next year requested to raise the premium for silver plans by another 24 percent. PacificSource Health Plans, which had filed for an average 7.4 percent increase on its Montana plans, requested another 11.3 percent raise to its silver plans.

“My department was advised by both companies just months ago, that with or without CSR payments, they would be able to honor the rates they provided to us and the public. Today, by their actions, they inform me that was not true,” Montana commissioner Matt Rosendale said in a statement.

Insurers have expressed varying degrees of frustration with the process.

Ken Provencher, president of the regional insurer, PacificSource Health Plans, said that in the three states where his company sells plans on the exchange the regulators all asked for slightly different assumptions regarding whether the payments would be made.

“The great ironic thing is that we actually struggled in the individual market in the first three years of the ACA and constantly refined our strategy. In 2017, we’ve actually seen some stability,” Provencher said. “We feel like we’re in a reasonably comfortable place to offer coverage to the market.”

In Idaho, regulators had the company file two sets of rates.

Montana did not specify which scenario insurers should use, and his company assumed that the payments would be made — and was pushing for the state to approve higher rates.

In Oregon, health insurers had filed rates assuming the payments were coming. But the state, anticipating Trump’s move, had done the groundwork to figure out what sort of a premium increase would be necessary should they be canceled. By Friday afternoon, Oregon officials had already instructed insurers who participate on the exchange to file for a 7.1 percent increase for all silver plans, on top of the already-approved 2018 rates to compensate for the loss of CSRs.

“We’ve been preparing for this type of action since the day the administration hinted it might happen,” said Jake Sunderland, a spokesman for Oregon’s Department of Consumer and Business Services. “We’d already done the math and had a pretty good idea of what increase would be necessary to compensate for the missing funding.”

In Arizona, the two insurers that provide plans on the exchange filed their rates for next year with different assumptions about whether CSRs would be in place. But Arizona Department of Insurance spokesman Stephen Briggs said that BlueCross BlueShield of Arizona, the company that had filed assuming the payments would be made, had informed regulators they felt comfortable with their rate, either way.

Other states were still working toward a solution on Monday afternoon. Massachusetts asked insurers to submit two sets of rates, but approved standard rates assuming CSRs would be paid hours before the White House made the announcement they’d be ending. A spokesman for the Massachusetts Health Connector did not have an update Monday.

Maryland, which asked insurers to assume the payments would be made, was working toward making a decision on what to do about whether to permit higher rates on Monday.

In Washington, insurance commissioner Mike Kreidler requested insurers file two sets of rate proposals – one with CSR funding, one without. Rates will increase between 9 percent to 27 percent without the payments, according to spokesman Steve Valandra. He said in an email that it was extremely likely, but not final, that the higher rates would be permitted.