Open enrollment is underway for many employees, Medicare recipients, and those who purchase health insurance on their own through Affordable Care Act plans -- and many of those Americans will see significant price hikes.

Health insurance premiums for plans bought over the ACA marketplace will increase 114% on average if enhanced subsidies expire at the end of 2025, according to KFF, a nonpartisan health policy research group. About 22 million of the 24 million ACA marketplace participants -- including many self-employed and small-business workers -- receive those premium tax credits, which are a key issue in the ongoing government shutdown.

Contributing to that price increase, ACA insurers are raising premiums for next year by an estimated 26% on average, according to KFF, in part because those companies expect healthier people to drop coverage if the enhanced subsidies expire.

"What's not certain is whether the price you're seeing today is what it will actually be," said Louise Norris, a health policy analyst with healthinsurance.org. "If those subsidy enhancements get extended, or if they get modified and extended, you might end up paying a different premium than what you're seeing now."