As insurers grapple with continuing uncertainty surrounding 2018 Affordable Care Act (ACA) marketplaces, a new Kaiser Family Foundation analysis of initial filings in 21 major cities finds that changes in 2018 benchmark silver plan premiums are likely to range widely, from a decrease of 5 percent in Providence, R.I., to an increase of 49 percent in Wilmington, Del., without factoring in tax credits.

However, the analysis finds that preliminary rates will likely change, and some insurers have included additional rate increases or said they may revise their requests, depending on potential resolution of outstanding questions in federal policy.

Unlike in previous years, insurers in this market face new uncertainties that could affect their final rate requests, including questions about the degree to which the ACA’s individual mandate will be enforced, and about whether the Trump administration will continue making cost-sharing subsidy payments to insurers or Congress will clarifiy that the payments are authorized.

The analysis finds that the vast majority of insurers mentioned these uncertainties in their filings. Some insurers have factored it into their initial requests, with those assuming the individual mandate would not be enforced including an additional 1.2 to 20 percent increase, and those assuming cost-sharing subsidy payments would not continue applying additional increases ranging from 2 to 23 percent.

Other insurers indicated they’d raise their rates beyond their initial request — by 3 to 10 percent if cost-sharing subsidy payments end or the question remains unresolved, according to the analysis.

Most enrollees in the marketplaces receive a tax credit to lower their premium; these enrollees are protected from premium increases, though they may need to switch plans to take full advantage of the tax credit. For example, in the states analyzed, a 40 year-old making $30,000 per year would pay 3 percent less in 2018 compared to this year for the benchmark silver plan after tax credits are factored in.