The cost of caring for the uninsured added $1,017 to the average health insurance premium for families last year and $368 to the average individual premium, a “hidden health tax” that gives the insured a strong incentive to push for universal coverage, a new report says.

The report, issued by Families USA, a consumer advocacy group, is based on an analysis by Milliman Inc. of data from the federal Medical Expenditures Panel Survey and other public and private sources that quantified the cost of uncompensated care.

An estimated 46 million Americans are uninsured, and according to the study, when they receive medical care, 37 percent of the cost is paid out of their own pockets, 26 percent is paid by charities, the government and others, and the rest, about $42.7 billion, is uncompensated.

Providers offset that cost by charging insurers more for their members’ care, the report says, and insurers pass it on as higher premiums, the hidden “tax.”

“As more people join the ranks of the uninsured, the hidden health tax is growing,” said Ron Pollack, executive director of Families USA, in a news release. “That tax hits America’s businesses and insured families hard in the pocketbook, and they therefore have a clear financial stake in expanding health coverage as part of health reform.”

U.S. Sen. Max Baucus, D-Mont., chairman of the Senate Finance Committee, said in the news release that the report points to the need for passing comprehensive health care reform this year. “We must repeal this hidden tax and lift the burden from American families and businesses by ensuring quality, affordable health care for all Americans,” he said.

A previous Families USA report had quantified the “tax” in 2005 at $922 for families and $341 for individuals. Given the economic downturn and the number of people who have lost their jobs and their health coverage, Pollack said, it’s likely that the “tax” will be “considerably higher” this year.

Also in the news release, Dan Danner, president and CEO of the National Federation of Independent Business, said the report “shows that the market in which we buy our health care is filled with cross-subsidies, making it dysfunctional and unsustainable.”

“Until individuals understand how much they are really paying for their health care, costs cannot be brought under control,” he added.

“Until costs are addressed, we will continue to struggle with coverage.”

The full report is available online at www.familiesusa.org.