NEW YORK — It turns out running a jail can be even more expensive than previously thought.

A study released today examining what it actually costs to operate local lockups has found that a whole host of costs — from providing inmate health care to funding employee benefits — aren’t always covered as line items in a corrections department’s budget.

Instead, researchers from the nonprofit Vera Institute of Justice found those costs are sometimes covered by other county agencies or general funds, adding to the true costs of incarceration.

“Knowing the actual price of jail is fundamental to reform,” said Christian Henrichson, the report’s lead author. “Without a grasp of the costs, policymakers will not know the full scale of potential savings.”

Running the more than 3,000 county jails across the country, which nearly 12 million people pass through every year, is notoriously expensive and federal statistics put the price tag at about $22.2 billion.

But the Vera researchers, who surveyed 35 jails of all sizes from 18 different states with a combined average daily population of 64,920, found another agency besides the corrections department or sheriff’s office paid for costs representing between 1 percent and 53 percent of total jail costs.

The New York City Department of Correction, which runs the nation’s second-largest jail system with about 11,000 average daily inmates, has a $1.1 billion budget. But an additional $1.2 billion from outside the budget is spent on operations such as health care and education programs, researchers found.

In Boulder County, Colo., which has a $14 million annual jail budget for the 484 average daily inmates, another $4.6 million is spent on the jails from outside agencies. And King County Public Health paid $29 million in health care for Seattle, Wash., inmates last fiscal year, representing about 20 percent of all jail costs, the study found.