President Trump recently mused that instead of increasing federal spending by $440 billion mostly for ObamaCare-participating health insurance companies, Republicans should dole out that amount directly to ObamaCare enrollees to spend on their own healthcare.

Taking money from taxpayers only to give it back with strings attached isn’t the way to empower consumers. This approach, moreover, could trigger a “woodwork effect” that increases ObamaCare spending above the $1.3 trillion current law provides for over the next decade. Fortunately, Mr. Trump already demonstrated in his first term how to make coverage affordable for millions without destabilizing ObamaCare or costing taxpayers a dime.

The Affordable Care Act exempted from ObamaCare a type of health insurance called “short-term limited duration insurance.” The exemption shields those plans from ObamaCare regulations that cause premiums to double for healthy enrollees and that ration care for the sick.

When President Obama saw how many people preferred ObamaCare-exempt plans, he kneecapped the competition. For 20 years, presidents from both parties had allowed short-term plans to last up to 12 months. But in 2016 Mr. Obama prohibited them from lasting more than three months, which reduced consumer protections and stripped coverage from patients after they got sick.

In 2018 Mr. Trump removed those restrictions and freed those plans to offer greater protection. He clarified that federal law allows short-term plans to last 36 months and to offer renewal guarantees. Renewal guarantees give patients who develop expensive illnesses the perpetual right to re-enroll in their health plan at healthy-person premiums.

Multiple federal courts upheld Mr. Trump’s rule as a reasonable and valid interpretation of existing law—including its clarification that the law allows renewal guarantees to offer longer-term protection to people in short-term plans.

Freeing consumers from ObamaCare’s hidden taxes made coverage dramatically more affordable for the majority of enrollees. The Congressional Budget Office found that consumers could purchase a “comprehensive major medical policy” at premiums “as much as 60 percent lower than premiums for the lowest-cost bronze plan.” Premiums fell so much that people could afford health insurance without a government subsidy. Perhaps that’s why President Biden rescinded Mr. Trump’s action in 2024.

Congress can make health insurance affordable for millions, without spending a dime, by codifying Mr. Trump’s 2018 rule into law.

Critics worry that would destabilize ObamaCare. But if that were true, it would have happened while the rule was in effect from 2018 to 2024. In the years leading up to the Trump rule, ObamaCare premiums soared at an average annual rate of 20%. In the six years when the Trump rule was in effect, ObamaCare premiums remained flat or fell and enrollment grew from 12 million to 24 million. In the two years since Mr. Biden rescinded Mr. Trump’s rule, ObamaCare premiums have risen a cumulative 31%.

Opponents will invoke the specter of low-quality coverage. Mr. Trump should relish that conversation. Across many dimensions, his rule produced higher-quality coverage than ObamaCare.

One of Mr. Biden’s economic advisers, Michael Geruso, found that ObamaCare creates irresistible incentives for insurers to ration care for the sickest patients. When ObamaCare enrollees complain about surprise bills and prior authorization, those regulations are often the cause. The Trump rule freed consumers from those perverse incentives. The Congressional Budget Office said Mr. Trump’s comprehensive policies often had lower deductibles and wider provider networks than ObamaCare plans.

Mr. Trump’s rule even offered longer-term contractual protection than ObamaCare plans do. It clarified that insurers could offer plans that last up to 36 months and offer even longer protection with renewal guarantees, so that even if you get cancer, you can keep enrolling in unlimited consecutive health plans at healthy-person premiums. Federal courts upheld Mr. Trump’s rule, including the part about renewal guarantees, as a valid interpretation of existing law. By contrast, ObamaCare requires insurers to commit only to 12 months of coverage

Mr. Trump’s rule made coverage better and more affordable because it removed government barriers that had prevented health plans from offering protections consumers want. Longer contractual terms and renewal guarantees protect consumers. Lower premiums protect consumers. Choice and innovation protect consumers.

Mr. Trump showed Congress how to make coverage affordable for millions without destabilizing ObamaCare or spending a single penny. All Congress has to do is make permanent the freedom Mr. Trump restored but Mr. Biden rescinded.