Prices hospitals charge for their services will all go online Jan. 1 under a new federal requirement, but patient advocates say the realities of medical-industry pricing will make it difficult for consumers to get much out of the new data.

A new federal rule requires all hospitals to post online a master list of prices for the services they provide so consumers can review them starting Jan. 1.

The health care industry nationally has a reputation for having little price transparency, which can make it difficult for consumers to price compare. But the hospital’s master list prices, sometimes called a chargemaster, is also not a complete look, consumer advocates say.

That’s because the final bill a patient receives is almost never the same as the sticker price for the services they received. Insurance companies negotiate discounts on the sticker prices. Co-pays, co-insurance, deductibles also add other layers of complexity that bring discounts or increased costs before a final charge is determined.

“The list prices are so high that the vast majority of hospitals don’t even try to collect list prices from uninsured patients,” said Benedic Ippolito, with the American Enterprise Institute, who has researched hospital list prices.

The federal rule is being brought out as a measure to improve competition and help educate consumers.

“We are just beginning on price transparency,” Seema Verma, head of U.S. Centers for Medicare & Medicaid told the Associated Press. “We know that hospitals have this information and we’re asking them to post what they have online.”

But real transparency comes when consumers can easily see what they will pay to a provider based on their insurance benefits, said Thomas Campanella, Baldwin Wallace University health care MBA program director. He said some insurance companies are providing that information through price comparison tools. “I almost see it being more of a political ‘look at what we did,’” Campanella said of the requirement to post list prices.

A benefit of having health insurance is that the insurance companies negotiate with hospitals on a discount from what is listed on the chargemaster. If a hospital is “in network” it means the insurer and hospital have an agreement on discounted rates and the insurance company typically covers a higher portion of those prices. If a patient goes to a medical provider that is out-of-network, they could be billed the difference between what the chargemaster lists as the price and what their insurance writes a check for. The practice is called balance billing or sometimes called “surprise billing.”

Miranda Creviston Motter, president and CEO of Ohio Association of Health Plans, which represents insurance companies, said as health care costs continue to rise, provider cost information is important and the association supports federal policies requiring providers to provide easy to understand cost information directly to health care consumers.

“This information supplements the cost information health plans currently offer their members. ,” she said in a statement.

Price comparison tools are becoming increasingly available through insurance companies, but they have limits in usefulness. Not all health care costs can be shopped for ahead of time, such as emergency visits, and consumers can prioritize other things besides cost, such as a doctor they trust or a hospital close to home. Only a small number of employees at two large companies with a price transparency tool used the tool and it was not associated with lower health care spending, according to 2016 study in the Journal of the American Medical Association.

Scott McGohan, CEO of McGohan Brabender, a benefits broker, said while many of the major insurance carriers have price shopping tools, it’s not always easy to know enough about medicine to know how to price shop.