The Obama administration is delaying enforcement of another provision of the new health care law, one that prohibits employers from providing better health benefits to top executives than to other employees.
Tax officials said they would not enforce the provision this year because they had yet to issue regulations for employers to follow.
The Affordable Care Act, adopted nearly four years ago, says employer-sponsored health plans must not discriminate "in favor of highly compensated individuals" with respect to either eligibility or benefits. The government provides a substantial tax break for employer-sponsored insurance, and, as a matter of equity and fairness, lawmakers said employers should not provide more generous coverage to a select group of high-paid employees.
But translating that goal into reality has proved difficult.
Officials at the Internal Revenue Service said they were wrestling with complicated questions like how to measure the value of employee health benefits, how to define "highly compensated" and what exactly constitutes discrimination.
Bruce I. Friedland, a spokesman for the I.R.S., said employers would not have to comply until the agency issued regulations or other guidance.
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President Obama signed the health care law in March 2010. The ban on discriminatory health benefits was supposed to take effect six months later. Administration officials said then that they needed more time to develop rules and that the rules would be issued well before this month, when other major provisions of the law took effect.
A similar ban on discrimination, adopted more than 30 years ago, already applies to employers that serve as their own insurers. The new law extends that policy to employers that buy insurance from commercial carriers like Aetna, Cigna, Humana and WellPoint, or from local Blue Cross and Blue Shield plans.
This could eventually be a boon to workers, the administration says.
"Under the Affordable Care Act, for the first time, all group health plans will be prohibited from offering coverage only to their highest-paid employees," said Erin Donar, a Treasury spokeswoman. "The Departments of Health and Human Services, Labor and the Treasury are working on rules that will implement this requirement."
The enforcement delay is another in a series of deadline extensions, transition rules, policy shifts and other steps by the Obama administration to minimize disruption from the new health care law, which is sure to be invoked by both Democrats and Republicans running for office this fall.
In recent months, the administration has delayed a requirement that larger employers offer coverage to full-time employees and delayed online enrollment in the federal insurance exchange for small businesses. It waived major provisions of the 2010 health law so consumers could renew policies that would otherwise have been canceled or terminated because they did not meet the law's coverage requirements.
In addition, federal officials announced that people with canceled insurance policies could obtain hardship exemptions sparing them from tax penalties if they went without insurance this year.
One of the questions facing the I.R.S. is whether an employer violates the law if it offers the same health insurance to all employees but large numbers of low-paid workers turn down the offer and instead obtain coverage from other sources, like a health insurance exchange.
Some health insurance arrangements will almost surely be forbidden, officials said. For example, they said, employers will not be able to provide coverage only to management.
Likewise, the officials said, a company could not provide free coverage to "highly compensated individuals" while requiring other employees to pay, for example, 25 percent of the cost. In addition, they said, benefits available to the dependents of highly paid executives must be available on the same terms to dependents of other employees in the health plan.
Under the 2010 law, an employer that has a fully insured health plan that discriminates in favor of high-paid executives could face a steep penalty: an excise tax of $100 a day for each individual affected negatively.
Thus, if a company had 100 employees and its health plan were found to discriminate in favor of 15 executives, the employer could be subject to a tax penalty of $8,500 for each day of noncompliance, for the 85 employees discriminated against. If the discrimination continued for 10 days, the penalty could be as much as $85,000.
If a company with 60 employees failed to meet the new standards with respect to half its employees for a year, it could face a penalty of $1 million.
One reason for the delay in enforcement is that officials have decided to review the existing nondiscrimination rules for self-insured companies, even as they try to write new rules for employers that buy commercial health insurance.
The existing restrictions on self-insured health plans are "outdated, inadequate and unworkable," said Kathryn Wilber, a lawyer at the American Benefits Council, which represents many Fortune 500 companies.
Under the earlier law, all health benefits provided to highly compensated individuals — with the possible exception of certain executive physicals — are supposed to be provided to rank-and-file employees.
But employers say they may have legitimate reasons for wanting to offer different benefits to different workers.
"Employers should be permitted to provide lower-cost coverage to employees who may not be able to afford the comprehensive coverage being provided to other employee groups," Ms. Wilber said.
Katie W. Mahoney, the executive director of health policy at the U.S. Chamber of Commerce, said the existing nondiscrimination rules were so convoluted that employers often complied just with the spirit of the law, "rather than with the precise requirements of the regulations."
"Employers are likely to have difficulty complying with the new nondiscrimination requirement" as well, Ms. Mahoney said.
She said the administration should scrap the existing rules and replace them with "a single set of nondiscrimination rules and a single set of penalties for all types of group health plans."
—By NYT's Robert Pear