WASHINGTON -- The average family with health insurance in 2008 paid a "hidden health tax" of $1,017 to cover the health-care costs of the uninsured, according to a report released Thursday by advocacy group Families USA.

The report by the group, which promotes universal health insurance, found that a total of $42.7 billion in care for those without insurance was passed on to health insurers. The insurers, in turn, passed on the costs through higher premiums, the report said.

The...