In an analysis of what Affordable Care Act (ACA) exchange insurers are requesting to charge customers in 21 major cities in 2018, the Kaiser Family Foundation found the cost for the second-lowest silver-level plan will range from $244 to $631 per month, with most enrollees cushioned from the price hikes by federal subsidies.

Percentage-wise, the changes range from a 5 percent drop in Providence, Rhode Island, (the only city on the list seeing a decrease in premiums) to a 49 percent increase in Wilmington, Delaware, (which is the $631 per month figure mentioned above) based on a 40-year-old customer who doesn’t smoke and makes $30,000 per year. After accounting for the ACA subsidy, the premium in all states would be $201 per month, a 3 percent drop from last year’s post-subsidy rate.

These rates can change, with insurer deadlines varying from state to state. For exchanges that use the federal Healthcare.gov site, insurers will have to finalize their 2018 rates by the end of September and then can’t revise their rates or service areas until the following year. Between the attempts to repeal and/or replace the ACA and the Trump administration’s moves on not enforcing the individual mandate or possibly pulling cost-sharing reduction (CSRs) subsidies to insurers, plenty of uncertainty remains for insurance companies, which Kaiser researchers said is being priced into rate requests.

“Some states have attempted to standardize the process by requesting rate submissions under multiple scenarios, while other states appear to have left the decision up to each individual company,” the Kaiser analysis said. “There is no standard place in the filings where insurers across all states can explain this type of assumption, and some states do not post complete filings to allow the public to examine which assumptions insurers are making.”

Insurers assuming the Trump administration won’t enforce the individual mandate are requesting an additional hike of up to 20 percent above their rate request, a figure that was cited by multiple insurers, including Maryland’s CareFirst Blue Choice and New Mexico Health Connections. If CSRs are either cut or not guaranteed, insurers said they would raise rates by an additional 3 to 10 percent above their initial request, or by as much as 38 percent when the increases would only apply to silver-level plans.

The analysis also showed a decrease in insurer participation since the exchanges opened. In 2014, the 20 states (plus the District of Columbia) analyzed by Kaiser had an average of 5.7 insurers participating per state. That rose to a high of 6.7 in 2015 and has fallen ever since, down to 5.1 in 2017 and a projected 4.6 in 2018. The state with the biggest requested hike, Delaware, is also the only one on the list with only a single participating insurer after Aetna’s exit.