Most states are served by HealthCare.gov, where premiums for a “benchmark” silver plan for 2022 will be about 3 percent lower, on average, than this year, according to a report from the federal government. (Plans are designated by metal levels. Bronze plans generally have the lowest monthly premiums, and the premiums get progressively higher with silver, gold and platinum plans.) Tax credits that reduce the cost of premiums are calculated based on the cost of the benchmark silver plan, which can change from year to year.

In some state-based marketplaces, premiums may increase “modestly” on average, Kaiser said. Seventeen states — including Kentucky, Maine and New Mexico, which added their own exchanges this year — and the District of Columbia run their own marketplaces.

On average, the government said, people in HealthCare.gov states will have a choice of more than 80 health plans, up from an average of 46 plans this year.

Most significant, however, is that under the American Rescue Plan Act, financial help for health coverage has been expanded for this year and next for both lower- and middle-income people.

The dollar amount of premium tax credits has risen, and they now cover the full cost of enrolling in a benchmark plan for people with incomes up to 150 percent of the federal poverty level — about $19,000 for a single person, and $33,000 for a family of three, according to a Kaiser analysis. That means families at that income level can get premium-free silver plans. Before, they had to pay more than 4 percent of household income for a benchmark plan.

In the past, plans with low premiums often had significant deductibles — the amount paid out of pocket, before insurance started paying — which discouraged some people from enrolling, Ms. Pollitz said. “Now, there are zero-premium plans with low deductibles, and that really is significant,” she said.

The pandemic aid law also expanded eligibility for premium help to people with higher incomes — over 400 percent of the poverty level ($51,520 for a single person, and about $88,000 for a family of three). Now, those families won’t have to contribute more than 8.5 percent of their income. Previously, such plans could easily cost more than 20 percent of income for older people because premiums are based on a person’s age, Ms. Pollitz said.