WASHINGTON >> Older people with low incomes nearly everywhere would have access to free “Obamacare” health coverage next year, according to a study today that found the Trump administration’s efforts to undercut the Affordable Care Act have broad unintended consequences.

The analysis by the consulting firm Avalere Health found that in nearly 98 percent of counties served by HealthCare.gov, a 50-year-old making about $18,000 a year would be able to get a basic “bronze” plan for no monthly premium in 2018.

A four-person household headed by a hypothetical 50-year-old could make nearly $37,000 and be eligible for free “bronze” coverage. The study covers the 39 states served by the federal HealthCare.gov website, but similar effects are expected in states running their own online insurance markets.

“I’m actually fascinated to see what this does,” said Chris Sloan, a senior manager who worked on the report. “We know that an awful lot of people shop every year. This may make some of the expected enrollment losses not as big as they could have been for next year.”

Sign-up season for taxpayer-subsidized individual health plans got underway this week after some major changes by the Trump administration. Those include a shorter enrollment window that lasts until Dec. 15, and deep cuts in advertising and consumer assistance.

The free insurance quirk is the result of President Donald Trump’s decision to end payments that reimbursed insurers for providing lower copays and deductibles to low-income customers. To offset losses, the companies raised premiums for popular “silver” plans, which automatically boosted federal subsidies.

But premiums didn’t go up as much for basic “bronze” plans and higher-tier “gold” plans, so more customers can now get those plans for no added cost, provided their incomes qualify for subsidies.

People making up to four times the poverty line, or about $48,000 for an individual, can get federal help. “Bronze” plans aren’t for everyone, because they have very high deductibles.

In a statement, the Trump administration said “Obamacare’s” problems keep getting worse, but avoided the question of whether its own actions are contributing.

About 9 million to 10 million people are currently enrolled through the health law’s markets. Also, nearly 8 million uninsured people could qualify for subsidies.

The free insurance twist is no help to millions of consumers who don’t qualify for subsidies. They face another year of steep increases.