Workers get portable insurance, and the chance to select their own plan, while businesses can avoid the paperwork and bureaucracy that comes with running a health plan for their employees.

Last Thursday afternoon, the Trump administration released its final rule regarding Health Reimbursement Arrangements (HRAs). The 497-page document will take lawyers and employment professionals weeks to absorb and digest fully. But in a nutshell, the rule will help to make coverage more portable and affordable—while also going a long way to resolve the problem of pre-existing conditions.

As I first explained when the administration proposed this HRA rule back in October, much of the problem surrounding pre-existing conditions revolves around portability. Because most Americans don’t own their own health coverage—their employers do—when people lose their job, they lose their health coverage. The pre-existing condition problem emerges when people develop a costly medical condition while at one job, then have to switch jobs or otherwise leave their employer plan.

Solving the portability problem—allowing health coverage to go from job to job—would go a long way towards solving the pre-existing condition problem. Of course, Democrats don’t talk about solving the portability problem because they don’t want to solve it. They want the government to control everything through a single-payer health care system. That’s why they spend so much time talking about a symptom (people with pre-existing conditions who can’t get coverage) rather than the underlying disease (coverage not being portable).

But if people owned their own insurance policies, they could change jobs easily, without fear of losing their coverage. Moreover, they would get to pick the kinds of benefit designs and doctor networks they want, rather than being stuck with what their employer picks for them.

The final rule accomplishes both objectives. It enhances portability by allowing employers to give their workers a (tax-free) contribution to an HRA, so employees can buy the plan that works best for them. If there’s any difference between the employer’s contribution and the total premium—for instance, an employer contributes $300 per month, and the worker selects a plan with a $350 monthly premium—the worker can pay the difference on a pre-tax basis, so long as he purchases the plan outside of the Obamacare exchanges. Best of all, because employees own the plans and not the employer, they can keep their coverage when they change jobs.

This change also improves affordability, in two key respects. First, individuals can buy just the coverage they want, rather than the coverage their employer gives them. Currently, if an employer plan offers particular benefits that an employee does not value, or a provider network a worker does not need, the worker can only buy an alternative plan by forfeiting their employer’s subsidy towards their health insurance—an unattractive and irrational option for most. The HRA option will allow workers to retain their employer’s subsidy, yet purchase more tailored coverage.

Second, more people purchasing coverage individually will create a more robust marketplace, increasing competition. Carriers may move into the market for individual coverage, and even create new options to attract additional business—both changes that will help consumers, and mitigate premium increases.

The final rule does include important safeguards to ensure that businesses don’t just try to “dump” their sickest employees onto individual insurance plans, raising premiums on the Obamacare exchanges. Most notably, if they elect the HRA option, firms must apply it to an entire class of workers—for instance, all full-time workers, or all workers in a certain geographic area. Moreover, employers cannot vary their contributions to workers’ HRAs, except by the employee’s age and number of dependents.

The rule could eventually lead to dramatic changes in Americans’ health-coverage options, but it includes provisions designed to phase those changes in over time. Under the rule, employers cannot offer traditional group health coverage to any class of workers that has access to an individual coverage HRA. In other words, employers can choose the “new” HRA model to deliver benefits to their workers, or the “old” (i.e., existing) model for their workers, but not both (at least not for the same class of workers).

However, the final rule also includes a critically important grandfathering provision, which will provide businesses the option for a smoother transition. Under this provision, an employer can apply the HRA model to new hires, while allowing existing employees to maintain their traditional group insurance. For instance, an employer could state that any worker joining the firm after the HRA rule takes effect (on January 1, 2020) would receive health coverage using the new rules, while current workers would remain on the firm’s existing employer plan.

The HRA rule represents the last element of President Trump’s October 2017 executive order on health care (the others being short-term insurance and Association Health Plans)—and potentially the most significant. The HRA coverage option presents a “win-win” for both employees and employers: Workers get portable insurance, and the chance to select their own plan, while businesses (particularly small businesses) that select this option can avoid the paperwork and bureaucracy that comes with running a health plan for their employees.

Conservatives concerned about pre-existing conditions should study this rule closely, and cite it every time the left mounts political attacks over the issue. Liberals want the government to control all of health care, as evidenced by their single-payer push. Conversely, conservatives want doctors and patients to make their own health-care decisions. Last week’s HRA rule will accomplish just that.