A report by the Vera Institute of Justice, with offices in New York, Washington and New Orleans, found among the 40 states that responded to a survey, the total fiscal year 2010 taxpayer cost of prisons was $38.8 billion, or $5.4 billion more than in state corrections budgets for that year.
Michael Jacobson, the institute's director, said when all costs are considered, the annual average taxpayer cost in these states was $31,166 per inmate.
To calculate the total price of prisons, Vera developed a survey tool that tallied costs outside corrections budgets.
The study found the most common of these hidden costs were fringe benefits, underfunded contributions for corrections employees' pension and retiree healthcare plans, inmate healthcare, capital projects, legal costs, and inmate education and training.
The scale of the expenditures outside of corrections departments ranged from less than 1 percent of the total cost of Arizona's prison budget to 34 percent in Connecticut.
For example, the Connecticut Department of Corrections spent $613.3 million for prisons in fiscal year 2010, but when all state costs are included, the total taxpayer cost was $929.4 million, the study said.