The numbers come from an analysis from the McKinsey Center for U.S. Health System Reform, which did the work of examining all the plans and matching 2015 products with 2016 offerings. McKinsey examined the larger market areas that insurance companies use to set their rates, instead of individual counties. That means that our estimate of terminated plans may be an undercount, because there are some additional counties where renewing customers will be out of luck.

Our advice from last year still applies. Even people who aren’t forced back into the marketplace could be well served by examining their options. The McKinsey analysis finds that, in many markets, people willing to switch plans could experience significant savings on their premiums. A government analysis, which looked at all the plans people currently hold, found that more than 80 percent of federal marketplace shoppers could find a better deal if they were willing to switch. And a report from the Kaiser Family Foundation published Wednesday estimated that renewers in the kind of plan we looked at would benefit from switching in 73 percent of counties.

And some of the 2016 plans that are considered renewals really aren’t identical to their 2015 counterparts; they may have subtle changes in what customers have to pay for or what services are covered. The government’s website for the marketplaces in most states, HealthCare.gov, is set up to provide more information about the differences between plans this year.

Of course, switching insurance plans may mean even bigger changes. Different plans may have different structures of deductibles and other out-of-pocket payments. They may also mean switching to new doctors or other caregivers. My colleague Abby Goodnough has written about some Obamacare shoppers who are planning to switch plans for the third time this year. Many have found the shifts disorienting, even as they welcome new choices that didn’t exist before the Obamacare market existed.