Most states reimburse foster parents significantly less than the actual cost of raising a foster child, complicating the task of finding good homes for children who need them, according to a first-of-its-kind survey.

The survey analyzed regional living expenses and calculated on a state-by-state basis the minimum cost of adequately raising a foster child. Only Arizona and the District of Columbia pay foster parents more than this minimum amount, according the survey.

To adequately cover the cost of rearing a foster child, base payments in 28 states would need to be raised at least 50 percent, and five states — Idaho, Missouri, Nebraska, Ohio and Wisconsin — would need to more than double their current base rates, according to report. It was compiled by the University of Maryland School of Social Work, the National Foster Parent Association, and Children's Rights, a New York-based advocacy group, for release Wednesday.

Of the more than 500,000 U.S. children in foster care at any given time, about 75 percent live with foster parents, while most of the others are placed in group homes and institutions.

The report expressed concern that inadequate reimbursement rates would worsen a shortfall of foster parents, "potentially increasing the likelihood that children will be placed in institutions or shuttled from one foster placement to another."

"The bottom line is that when these rates don't reflect the real expenses that foster parents face, it's the children who suffer," said Karen Jorgenson, executive director of the Foster Parent Association.

Although child welfare agencies are required by federal law to reimburse foster parents for the cost of raising foster children, there is no national minimum, leaving states and localities free to set their own rates. The result is a huge disparity. The base rates paid for raising a 2-year-old foster child range from $236 a month in Nebraska to $869 in the District of Columbia.

The "minimum adequate rates" in the report represented the cost of providing basic needs — housing, food, clothing, and school supplies — as well as a child's participation in normal after-school sports and activities.

The monthly rates recommended by the report, averaged out on a national basis, were $629 for 2-year-olds, $721 for 9-year-olds and $790 for 16-year-olds. Currently, the average actual monthly base rates offered by states are $488 for 2-year-olds, $509 for 9-year-olds and $568 for 16-year-olds.

While Arizona and the District of Columbia were the only jurisdictions whose base payments exceeded the recommended minimums, 10 other states fell short by only small amounts: Alaska, Connecticut, Indiana, Kentucky, Maryland, Nevada, Tennessee, Texas, West Virginia and Wyoming.

In Nebraska, state officials had advance knowledge that the report would list it as having the lowest base rate, and the administrator of its Child Welfare Unit, Christine Hanus, sent a letter to Children's Rights expressing dismay.

Hanus noted that many Nebraska foster parents receive more than the minimum base rate, as well as extra payments for child care and other purposes. However, she acknowledged in the letter that two-thirds of the payments for foster children under 6 were at the base level of $236 a month — far below the minimum adequate rate of $636 which the report recommended for Nebraska.

In a telephone interview, Hanus said Nebraska's foster parents were meeting the needs of the children in their care.

"Foster parents do not leave because of the money or the care rates," she said.

In Missouri, Department of Social Services Director Deborah Scott noted the state recently increased subsidies to foster parents for the first time since 2001, but acknowledged the rates were still below recommended guidelines.

Julie Farber, director of policy for Children's Rights, said she hoped child welfare officials in states with low rates would use the report to press their legislatures for more funding.

In California, Farber said, the number of foster parents has been dropping, and child welfare officials already have cited inadequate reimbursement as a factor.

"They know it stands in the way of doing their job," she said.