WASHINGTON—Government regulators in just a month nearly doubled the number of “mini-med” plan sponsors that have been granted one-year waivers from meeting certain requirements of the federal health care reform law.

As of Friday, the most recent data available, the Department of Health and Human Services had approved requests from 222 mini-med plan sponsors with a total of 1.5 million plan enrollees for one-year waivers. That's up from 117 sponsor waivers affecting 1.18 million enrollees as of Nov. 1 and 30 waivers affecting nearly 969,000 enrollees as of Sept. 30.

Many of the most recent waivers were granted to local union health care funds. In all, nearly three dozen waivers involve union funds.

The waiver affecting the largest group of enrollees was granted in September to the United Federation of Teachers Welfare Fund in New York, whose mini-med plan has 351,000 enrollees, according to its filing.

The waivers are needed because most, if not all, mini-med plans run afoul of federal rules—mandated by the health care reform law—that set a minimum annual dollar limit on essential benefits that health care plans must provide in 2011, 2012 and 2013. The minimum limit is $750,000 in 2011, $1.25 million in 2012 and $2 million in 2013.

Starting in 2014, the law bars annual limits for essential benefits.

The minimum limits, though, are far more than the maximum benefits provided through mini-med plans, which typically are offered to low-wage, part-time or seasonal employees.

Under the health care reform law, low-wage employees might qualify for government-subsidized coverage that will be available from insurers offering coverage through new state insurance exchanges starting in 2014, reducing the need for mini-med plans.

Until then, mini-med plan providers can obtain waivers from the required minimum annual benefit in situations where meeting those requirements would result in a significant decrease in access to benefits or significantly increase premiums, HHS said.

Sponsors are required to notify mini-med enrollees that they have received the waivers.