A newly issued set of rules will make it easier for some workers to change jobs by requiring healthcare plans and insurers to issue fewer “pre-existing condition” riders.

The rules could affect up to 10 percent of the nation’s workforce and a disproportionate number of smaller companies who will either lose workers or be forced to pay higher premiums due to conditions no longer exempted from their corporate policies.

Congress agreed to these changes more than eight years ago but opposition from small business groups and others forced numerous hearings before the final rulings were issued in late 2004.

The new rule, which becomes effective for health care plans starting July 1, is meant to implement more of the 1996 Health Insurance Portability and Accountability Act by making it easier to obtain group health coverage.

It limits when preexisting medical conditions can be excluded from coverage and requires group health plans and group health insurance issuers to offer "special enrollment" in certain cases.

The law, pushed through Congress by then-President Bill Clinton, was intended to guarantee access to health insurance for small businesses with 50 or fewer employees, and to require that insurers renew coverage for a person or group regardless of the health status of any member of the group.

"In an era when American workers often change jobs, and even careers, several times in the course of their lives, it is important that they are able to respond to the modern workplace without having to fear for their health insurance," said Health and Human Services Secretary Tommy Thompson last week.

Three federal agencies jointly issued the new rule based on the 1996 law. Bush administration officials said their rule "does not significantly modify the framework" the Clinton administration issued in April 1997 for implementing this part of the law.

Yet it took another 7½ years for the rule to be made final.

"We have listened to public comment and worked to craft a rule that will provide maximum protection for consumers, while minimizing the burden on health plans," said Medicare chief Mark McClellan.

When Clinton signed the law, his administration said it would affect about one in 10 U.S. workers - then an estimated 25 million Americans - and their families. Those were workers switching jobs, self-employed or with pre-existing medical conditions.