BOSTON The Trump administrations new attack on Obamacare will expose consumers to surprise, sometimes staggering medical bills.

Just ask some of the state officials who deal with these kinds of issues every day.

They are part of the National Association of Insurance Commissioners , which happened to be meeting in Boston this weekend, days after the U.S. Department of Health and Human Services (HHS) finalized new rules for short-term, limited-duration insurance policies.

These plans, which insurers have sold for decades, are supposed to provide minimal, temporary assistance for people with brief gaps in coverage. For that reason, they are not subject to the Affordable Care Acts regulations. Short-term policies do not have to cover mental health care, prescriptions, or other services that the 2010 health care law calls essential. And insurers dont have to sell these policies to people who have pre-existing medical conditions.

The Affordable Care Act didnt legislate short-term plans out of existence, but it allowed the federal government to regulate them aggressively. The Obama administration did just that, issuing rules that limited the plans to durations of no more than three months.

Obama officials also decided that short-term plans wouldnt count toward the individual mandate, meaning that people who bought those plans would owe a financial penalty for not having comprehensive coverage.